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Well structured WBBSE Class 10 Physical Science MCQ Questions Chapter 6 Current Electricity can serve as a valuable review tool before exams.

Current Electricity Class 10 WBBSE MCQ Questions

Multiple Choice Questions :

Question 1.
The SI unit of electric charge is:
(A) Coulomb
(B) Ampere
(C) Ohm
Answer:
((A) Coulomb

Question 2.
The unit of potential difference is :
(A) joule
(B) volt
(C) ohm
(E) ampere
Answer:
(B) volt

Question 3.
The unit of electrical power is:
(A) volt
(B) watt
(C) ohm
(D) joule
Answer:
(B) wait

Question 4.
What material an electric fuse made of?
(A) copper
(B) silver
(C) iron
(D) tin-lead alloy
Answer:
(D) Tintead alloy

Question 5.
Unit of resistance is:
(A) ampere
(B) ohm
(C) coulomb
(D) joule
Answer:
(B) ohm

Question 6.
Specific resistance of a conductor dipends on :
(A) its length
(B) its cross-sectional area
(C) its material
Answer:
(C) its nateriat

Question 7.
The amount of heat developed due to current can be known from:
(A) Ampere’s law
(B) Ohm’s law
(C) Joules law
Answer:
(C) Joules lau

Question 8.
The example of conservation of electrical energy into mechanical energy is:
(A) electric cell
(B) electric motor
(C) electric lamp
Answer:
(B) electric motor

Question 9.
The action of electric current on magnet was first observed by:
(A) Oerested
(B) Joule
(C) Barlow
(D) Newton
Answer:
(A) Oerested

Question 10.
Ohm’s law is related to:
(A) current and potential difference
(B) volume and pressure
(C) temperature density.
Answer:
(A) current and potenitial difference

Question 11.
Electric supply company measures the electricity consumed by the consumers in their household in terms of :
(A) joule unit
(B) watt-hour
(C) B.O.T. units
Answer:
(C) B.OT inits

Question 12.
Which one is not conductor of electricity:
(A) copper
(B) gold
(C) aluminium
(D) plastic
Answer:
(D) plastic

Question 13.
Ammeter measures:
(A) resistance
(B) potential difference
(C) current
Answer:
(C) current

Question 14.
Potential difference is measured by:
(A) Voltmeter
(B) Volameter
(C) Galvanometer
Answer:
(A) Voltmeter

Question 15.
If the length of the conductor is kept unaltered and cross section of conductor is increased then its resistance:
(A) increases
(B) decreases
(C) remains unaltered
Answer:
(B) decreases

Question 16.
If the corss section of the conductor is kept unaltered and length of conductor is increased then its resistance:
(A) increases
(B) decreases
(C) remains unaltered
Answer:
(A) increases

Question 17.
The correct relation is :
(A) Watt = \(\frac{\text { Volt }}{\text { Ampere }}\)
(B) Watt = \(\frac{\text { Ampere }}{\text { Volt }}\)
(C) Watt = Volt × Ampere
Answer:
(C) Watt = Volt × Ampere

Question 18.
The physical quantity measured by kilowatt-hour
(A) Electric power
(B) Electric energy
(C) Current
Answer:
(B) Electric energy

Question 19.
What is the equivalent resistance of the resistances 2 ohm, 3 ohm and 5 ohm combined in parallel ?
(A) 10 ohm
(B) \(\frac{30}{31}\) ohm
(C) \(\frac{31}{30}\) ohm
(D) 20 ohm
Answer:
(B) \(\frac{30}{31}\) ohm

Question 20.
What is the equivalnnt resistance of the resistances 3 ohm, 5 ohm and 12 ohm combined in series?
(A) 15 ohm
(B) 18 ohm
(C) 20 ohm
(D) 30 ohm
Answer:
(C) 20 ohm

Question 21.
Force between two charges separated by a certain distance in air is F. If each charge was doubled and distance between them also doubled, then force would be
(A) F
(B) 2 F
(C) 4 F
(D) F / 4
Answer:
(A) F

Question 22.
What is the dimensional formula of electric charge ?
(A) [M⁰ L⁰ TA]
(B) [M⁰ L⁰ T^-1 A]
(C) [M⁰ L⁰ TA^-1]
(D) [M⁰ L⁰ T^-1 A^-1]
Answer:
(A) [M⁰ L⁰ TA]

Question 23.
A charge q₁ exerts some force on a second charge q₂. If a hird charge q₃ be brought near, the force of q₁ exerted on q₂.
(A) decreases
(B) increases
(C) remains unchanged
(D) increases if q₃ is of same sign as q}₁ and decreases of q₃ is of opposite sign.
Answer:
The force between q₁ and q₂ is not affected by q₃.

Question 24.
The dimensional formula of electric density is
(A) MLT^-2 A^-1
(B) MLT^-3 A^-1
(C) ML² T^-3 A^-1
(D) ML² T^-3 A_-2
Answer:
(A) MLT^-3 A^-1

Question 25.
Electric flux at a point in an electric field is:
(A) positive
(B) negative
(C) zero
(D) none of these
Answer:
(C) zero

Question 26.
A soap bubble is charged to a potential of 16 V. Its radius is the doubled. The potential of the bubble now will be :
(A) 16 V
(B) 8 V
(C) 4 V
(D) 2 V
Answer:
(B) 8 V

Question 27.
A resistor of 0.5 Ω is connected to another resistor is parallel combination to get an equivalent resistance of 0.1 Ω. The resistance of second resistor is :
(A) 1/8 Ω
(B) 0.2 Ω
(C) 0.6 Ω
(D) 8 Ω
Answer:
(A) 1/8Ω

Question 28.
If six identical cells are each having emf of 6 V are connected in parallel the emf of the combination is :
(A) 1 V
(B) 1 / 6V
(C) 6 V
(D) 36 V
Answer:
(C) 6 V

Question 29.
The resistance of discharge tube is :
(A) ohmic
(B) non-ohmic
(C) both
(D) sometimes ohmic, sometimes non-ohmic.
Answer:
(B) non-ohmic.

Question 30.
A wire of resistance 1 W is stretched to double its length. The resistance will become
(A) 1/4
(B) 1
(C) 2
(D) 4
Answer:
(D) 4

Question 31.
A car battery has emf 12 V and internal resistance 5 × 10^-2 W. If it draws 60 A current, the terminal voltage of the battery will be
(A) 3 V
(B) 5 V
(C) 9 V
(D) 15 V
Answer:
(C) 9 V

Question 32.
The specific resistance of a wire depends upon :
(A) length
(B) cross sectional area
(C) mass
(D) none of these
Answer:
(D) None of these.

Question 33.
What is the unit for specific resistivity?
(A) Ohm-cm^-2
(B) Ohm-cm¹
(C) Ohm-cm
(D) Ohm-cm^-2
Answer:
(C) Ohm-cm

Question 34.
A battery having emf 4 V and internal resistance 0.5 W is connected with a resistance of 4.5 W, then the voltage at the terminals of battery is :
(A) 4.5 V
(B) 3.6 V
(C) 0 V
(D) 2 V
Answer:
(B) 3.6 V

Question 35.
The unit of specific conductivity is:
(A) ohm-cm^-1
(B) ohm-cm^-2
(C) ohm^-1-cm^-1
(D) ohm^-1 cm^-2
Answer:
(C) ohm^-1 cm^-1

Question 36.
The length of a wire is doubled. Its conductance will be :
(A) unchanged
(B) halved
(C) doubled
(D) quadrupled
Answer:
(B) halved.

Question 37.
Practical unit of resistance is ohm is equal to :
(A) 10⁹ emu
(B) 10⁷ emu
(C) 10¹¹ emu
(D) 10¹³ emu
Answer:
(A) 10⁹ emu

Question 38.
How many electrons constitute current of IA?
(A) 6.25 × 10⁹
(B) 6.25 × 10¹⁸
(C) 6.25 × 10⁵
(D) 6.25 × 10⁶
Answer:
(B) 6.25 × 10¹⁸

Question 39.
The resistance will be least in a wire with dimension
(A) L/2,2 A
(B) 2L, A
(C) L, A
(D) none of these
Answer:
(A) L/2,2A.

Question 40.
A cell of negligible resistance and emf 2V is connected to series combination of 2,3 and 5 ohm. The potential difference in vol across the 3 W resistance will be
(A) 6 V
(B) 3 V
(C) 2 / 3 V
(D) 0.6 V
Answer:
0.6 V

Question 41.
The material of a wire of a potentiometer is :
(A) copper
(B) steel
(C) manganin
(D) aluminium
Answer:
(C) magnanin.

Question 42.
Kirchhoff’s current law obeys conservation of :
(A) charge
(B) momentum
(C) energy
(D) none of these
Answer:
(A) charge.

Question 43.
Potentlometer measures potential more accurately because :
(A) It uses sensitive galvanometer for null deflection.
(B) It uses high resistance potentiometer wire.
(C) It measures the potential in the closed circuit.
(D) It measures the potential in the open circuit.
Answer:
(A) It uses sensitive galvanometer for null deflection.

Question 44.
A current loop placed in a magnetic field behaves like a:
(A) Magnetic dipole
(B) Magneitc substance
(C) Magnetic pole
(D) All are true
Answer:
(A) Magnetic dipole.

Question 45.
A charge + q is moving upwards vertically. It enters a magnetic field directed to the north. The force on the charged will be towards
(A) North
(B) South
(C) West
(D) East
Answer:
(C) West.

Question 46.
The vertical component of earth’s magnetic field is zero at a place where angle of dip is :
(A) 0°
(B) 45°
(C) 60°
(D) 90°
Answer:
(A) 0°

Question 47.
A magnetic needle suspended freely orients itself :
(A) in a definite direction
(B) in no direction
(C) upward
(D) downward
Answer:
(A) in a definite direction.

Question 48.
A material when placed in a magnetic field is thrown out of it. Then the material is :
(A) paramagnetic
(B) diamagnetic
(C) ferromagnetic
(D) non-magnetic.
Answer:
(B) diamagnetic.

Question 49.
Which of the following is an Ohmic resistance?
(A) diode value
(B) junction diode
(C) carbon-arc lamp
(D) nichrome
Answer:
(D) nichrome

Question 50.
For which of the following substances, resistance decreases with increase in temperature?
(A) copper
(B) mercury
(C) carbon
(D) platinum
Answer:
(C) carbon

Question 51.
In parallel combination of resistances –
(A) p.d. is same across each resistance
(B) total resistance is increased
(C) current is same in each resistance
(D) all of these are true
Answer:
(A) p.d. is same across each resistance

Question 52.
The main fuse is connected in :
(A) live wire
(B) neutral wire
C) both the live and earth wires
(D) both earth and neutral wire
Answer:
(A) live wire

Question 53.
The electric meter in a house records :
(A) charge
(B) current
(C) energy
(D) power
Answer:
(C) energy

Question 54.
When two negative charges are placed close together then :
(A) they attract each other
(B) they repel each other
(C) they become positive
(D) none of the above
Answer:
(B) they repel each other

Question 55.
If a source of EMF is traversed from negative to positive terminal, the potential change is :
(A) negative
(B) positive
(C) zero
(D) both negative\positive
Answer:
(B) positive

Question 56.
When the distance between the two charges are halved, the electrical force between the charges
(A) doubles
(B) reduces to one fourth
(C) halves
(D) quadraples
Answer:
(D) quadraples

Question 57.
Mercury behaves as a superconductor
(A) below 4.2K
(B) above 6.9 K
(C) below 23 K
(D) above 9.6 K
Answer:
(A) below 4-2 K

Question 58.
When a cell is in use, its emf E and terminal voltage v are related as :
(A) E = V
(B) E < V
(C) E > V
(D) none of these
Answer:
(C) E > V

Question 59.
Which one of the following behaves as a superconductor?
(A) platinum above 273 K
(B) mercury below 4.2K
(C) gold below -191°C
(D) fullerene at room temperature
Answer:
(B) mercury below 4.2K

Question 60.
If one of the resistors in a parallel circuit is removed, the total resistance will be :
(A) double
(B) same
(C) increased
(D) constant
Answer:
(C) increased

Question 61.
The flow of current in a circuit due to short circuit :
(A) reduces
(C) increases rapidly to dangerous level
(B) remains unchanged
(D) increases gradually
Answer:
(C) increases rapidly to dangerous level

Question 62.
If unit of I is ampere, unit of R is ohm, unit of t is second, then unit of H} is :
(A) Joule
(B) watt
(C) dyne / cm²
(D) ohm^-1
Answer:
(A) Joule

Question 63.
The relation between H, I, R and t is :
(A) H = I² R/t
(B) H/t = I²R
(C) R = I² t/H
(D) I² = HR/t
Answer:
(B) H/t = l² R

Question 64.
The filament of an incandescent bulb is ma e up of :
(A) tungsten
(B) aluminium
(C) copper
(D) nichrome
Answer:
(A) tungsten

Question 65.
Which of the following properties is not suitable for a fuse wire?
(A) low melting point
(B) high resistance
(C) thick and short in length
(D) thin and short in length
Answer:
(C) thick and short in length

Question 66.
The commercial unit of electrical energy we use is :
(A) wh
(B) kwh
(C) kw
(D) kilowatt.second
Answer:
(B) kwh

Question 67.
If an electrical appliance has E E R = 3.1, it is rated as :
(A) 2 star
(B) 3 star
(C) 4 star
(D) 5 star
Answer:
(D) 5 star

Question 68.
The electric meter in a house records
(A) energy
(B) current
(C) power
(D) charge
Answer:
(A) energy

Question 69.
Which one among the following is most energy efficient ?
(A) CFL
(B) tube light
(C) LED
(D) Incandescent lamp
Answer:
(C) LED

Question 70.
In a parallel circuit of bulbs
(A) same current exists in all the bulbs
(B) voltage across each bulb remains the same
(C) failure of any bulb leads to a break in the circuit
(D) All the above
Answer:
(B) voltage across each bulb remains the same

Question 71.
A current carrying conductor produces
(A) electric field
(B) magnetic field
(C) both
(D) none of these
Answer:
(B) magnetic field

Question 72.
A split ring in motion is called :
(A) armature
(B) rotor
(C) core
(D) commutator
Answer:
(d) commutator

Question 73.
The direction of an induced current can be predicted by :
(A) Ampere’s swimming rule
(B) Fleming’s left hand rule
(C) Fleming’s right hand rule
(D) Right-hand thumb rule
Answer:
(C) Fleming’s right hand rule

Question 74.
The frequency of alternating current supplied in India is :
(A) OHz
(B) 50 Hz
(C) 110 Hz
(D) 220 Hz
Answer:
(B) 50 Hz

Question 75.
Lenz’s law supports the principle of conservation of :
(A) mass
(B) energy
(C) momentum
(D) charge
Answer:
(B) energy

Question 76.
In commercial alternators, the rotor consists of
(A) armature coil
(B) brushes
(C) field magnets
(D) none of these
Answer:
(C) field magnets

Question 77.
The commercial generation frequency in India is :
(A) 50 Hz
(B) 60 Hz
(C) 100 Hz
(D) 150 Hz
Answer:
(A) 50 Hz

Question 78.
DC generators are also called :
(A) dynamo
(B) inverter
(C) storage cell
(D) alternator
Answer:
(D) alternator

Question 79.
The potential difference between the live wire and the neutral wire in domestic circuit is :
(A) 220 V
(B) 11 KV
(C) 33 KV
(D) 132 KV
Answer:
(A) 220 V

Question 80.
A switch must be connected in
(A) neutral wire
(B) live wire
(C) earth wire
(D) either live wire or neutral wire
Answer:
(B) live wire

Question 81.
Which of the two wires of a household ctrcuit are at the same potential?
(A) Live and Neutral
(B) Live & Earth
(C) Neutral and Earth
(D) None of them
Answer:
(C) Neutral and Earth

Fill in the blanks :

1. Coulomb = _____ × second.
Answer:
ampere

2. The equivalent resistance is smaller than the resistance in a parallel combination of _____ resistances.
Answer:
smallest

3. Potential difference = current × ______.
Answer:
resistance

4. 1² rt is some electrical _____.
Answer:
work

5. Power = potential difference × ______.
Answer:
current

6. Resistance of a wire is _____ proportional to the length of the wire.
Answer:
directly

7. A _____ is used to measure the potential difference between two points in a section of an electrical circuit.
Answer:
voltmeter

8. An ammeter is used to measure the _____ flowing through an electric circuit where the ammeter is connected in series.
Answer:
current

9. Short circuit occurs due to accidental direct contact of the live and the _____ wires.
Answer:
neutral

10. The total resistance of a number of resistors in series is equal to the ______ of the resistances of the component resistors.
Answer:
sum

11. Elecctomotive force is some _____ not a force.
Answer:
energy

12. In current electricity, the potential difference between two points is measured by the work done when unit _____ flows from one point to the other.
Answer:
charge

13. Potential difference between two points one _____ when work done to carry one coulomb charge between the points be 1 Joule.
Answer:
volt.

14. Resistance is the natural property of every material body by virtue of which the body _____ flow of electric charges through it.
Answer:
opposes

15. The current flowing through a conductor is directly proportional to the potential difference between its ends when _____ and other physical conditions of the conductor remain unaltered.
Answer:
temperature

16. Ohm’s law is not valid for current flowing through _____ under low pressure, electrolytes and semi-conductors.
Answer:
gases

17. If an electrical instrument of power 1 watt works for 1 hour, the electrical energy expended is known as 1 _____.
Answer:
watt-hour

18. Number of B.O.T. unit = \(\frac{\text { amphere } \times \text { volt }}{1000}\) × _____.
Answer:
hour

19. When electric current does not change the direction it is called _____.
Answer:
Direct Current.

20. Watt = Volt × _______.
Answer:
Ampere

21. The electro magnets are made using the _____ effect of electric current.
Answer:
magnetic

22. Usually the resistance of a conductor _____ with the rise in temperature.
Answer:
increases

23. The SI unit of current is _____.
Answer:
ampere.

24. In Ohm’s law, the _____ and other physical conditions are remaining constant.
Answer:
temperature

25. The temperature remaining constant, the resistance between two opposite forces of a unit cube of a conductor is called its _____.
Answer:
specific resistance.

26. The watt-hour is the practical unit of _____ energy.
Answer:
electrical.

27. Like charges _____ each other.
Answer:
repel

28. SI unit of electric potential is _____.
Answer:
volt.

29. Electric fuse is a _____, device.
Answer:
safety

30. Fleming’s left hand rule is also called _____ rule.
Answer:
motor.

31. An electric generator converts _____ energy into electrical energy.
Answer:
mechanical.

32. The other name of potential difference is _____.
Answer:
voltage

33. The amount of energy given to each coulomb of charge passing through a 12 V battery is _____ J.
Answer:
12

34. The unit of \varepsilon_0 (permitivity in vacuum) is _____.
Answer:
C² N^-1 m^-2

35. Resistivity of silver _____ with increase in temperature.
Answer:
increases

36. An ideal cell should have _____ internal resistance.
Answer:
zero

37. Mica is an _____.
Answer:
insulator

38. _____ filament is used in incandescent bulb.
Answer:
tungsten

39. Tube-lights are _____ power efficient than incandescent bulbs.
Answer:
more

40. CFLs and LED bulbs are _____ efficient than filament-type bulb.
Answer:
more

41. More the number of stars in an electrical appliance, _____ is its efficiency.
Answer:
higher

42. SI unit of magnetic field strength is _____.
Answer:
Tesla

43. The magnetic effect of current was discovered by _____.
Answer:
Oersted

44. The direction of induced current can be predicted by _____ law.
Answer:
Lenz’s

45. Laws of electromagnetic induction was proposed by _____.
Answer:
Faraday

46. In our houses, we have electric supply of frequency _____ Hz.
Answer:
50

47. In an alternator, the stator consists of the _____.
Answer:
armature.

48. The house wiring is done in a ______ system.
Answer:
tree

49. The earth wire should be connected to the _____ of the appliance.
Answer:
body

State whether the following statement is True or False : VSA

1. An ammeter is connected in series in a circuit and a voltmeter is connected in parallel.
Answer:
True

2. Electric current is the flow of charge.
Answer:
True

3. Electric current is vector quantity.
Answer:
False

4. All types of conductors obey ohma’s law
Answer:
False

5. Below 4.2K, mercury behaves as a superconductor.
Answer:
True

6. Resistance of materials in superconducting state is infinity high.
Answer:
False

7. If current flowing through a wire is doubled, the heat produced will also be doubled.
Answer:
False

8. An incandescent bulb is an energy efficient bulb.
Answer:
False

9. Watt is a much smaller unit of electrical power.
Answer:
True

10. We should buy electrical appliance with lower star-rating.
Answer:
False

11. Barlow’s wheel works on alternating current.
Answer:
False

12. At the centre of the circular loop, the magnetic field line is straight.
Answer:
True

13. Lenz’s law is in accordance with the law of conservaion of energy.
Answer:
True

14. A direct current can be stepped up for transmission.
Answer:
False

15. The earth is considered to be at zero potential.
Answer:
True

Well structured WBBSE Class 10 Physical Science MCQ Questions Chapter 7 Atomic Nucleus can serve as a valuable review tool before exams.

Atomic Nucleus Class 10 WBBSE MCQ Questions

Multiple Choice Questions :

Question 1.
Radioactive disintegration differs from a chemical change in being
(A) a nuclear process
(B) an exothermic process
(C) a sponteneous process
(D) a unimolecular first order reaction
Answer:
(A) a nuclear process

Question 2.
The phenomenon of radioactivity was first discoverd by –
(A) Rutherford
(B) Henry Becquerel
(C) Niels Bohr
(D) Madam curie
Answer:
(D) Modam curie.

Question 3.
a-rays consist of a stream of –
(A) H⁺
(B) He²⁺
only electrons
(D) only neutrons
Answer:
(B) He

Question 4.
Which of the following radiations, the one most easily stopped by air is –
(A) X-rays
(B) α-rays
(C) β-rays
(D) γ-rays
Answer:
(A) X-roys

Question 5.
γ-rays –
(A) consist of (+) ve particles
(B) are energy waves
(C) are deflected by an electric field
(D) have mass
Answer:
(B) are energy waves

Question 6.
A device used for the measurement of radioactivity is –
(A) mass spectrometer
(B) cyclotron
(C) nuclear reactor
(D) G-M-counter
Answer:
(D) G-M-counter

Question 7.
If a radioactive element is placed in an evacuated container, its rate of disintegration –
(A) will be increased
(B) will be decreased
(C) will change very slightly
(D) will remain unchanged
Answer:
(D) will remain unchanged

Question 8.
Emission of a β-particle by an atom of an element results in the formation of its
(A) isotope
(B) isomer
(C) isobar
(D) isomorph
Answer:
(C) isobar

Question 9.
Which of the following combinations will give the most stable nuclei?
(A) Odd Z and odd N
(B) Even Z and even N
(C) Odd Z and even N
(D) Even Z and odd N
Answer:
(B) Ever Z and even N

Question 10.
Stable nuclides cannot be obtained for –
(A) Z = 43, N = 35
(B) Z = 61, Z = 89
(C) A > 209
(D) All of these
Answer:
(D) All of thest

Question 11.
Which of the following nuclei are stable?
(A) \({ }_{28}^{60} \mathrm{Ni}\)
(B) \({ }_6^{11} \mathrm{C}\)
(C) \({ }_92²³3} \mathrm{U}\)
(D) \({ }_4^{8} \mathrm{Be}\)
Answer:
(D) \({ }_4^{10} \mathrm{Be}\)

Question 12.
Which of the following nuclel is unstable ?
(A) \({ }_5^{10} \mathrm{C}\)
(B) \({ }_7^{14} \mathrm{N}\)
(C) \({ }_8^{16} \mathrm{O}\)
(D) \({ }_4^{10} \mathrm{Be}\)
Answer:
(D) \({ }_4^{10} \mathrm{Be}\)

Question 13.
One becquerel of radioactivity of equal to –
(A) one disintegation/s
(B) two disintegration/s
(C) 6.023 × 10²³ disintegration/s
(D) three disintegration/s
Answer:
(A) one disintegation/s

Question 14.
The emission of beta-particles is from-
(A) the valence shell of an atom
(B) the inner shell of an atom
(C) the nucleus due to the nuclear conversion proton → neutron + electron
(D) the nucleus due to the nuclear conversion neutron → proton + electron.
Answer:
(D) the nucleus due to the nuclear conversion neutron → proton + electron.

Question 15.
Which of the following processes causes the emission of an x-ray?
(A) Alpha emission
(B) Gamma emissionz`
(C) Positron emission
(D) Electron capture
Answer:
(D) Electron capture

Question 16.
Loss of β-particle is equivalent to –
(A) increase of one proton
(B) decrease of one neutron
(C) combination of both (A) and (B)
(D) None of the above
Answer:
(C) combination of both (A) and (B)

Question 17.
Choose the incorrect one –
(A) 1 curie = 3.7 × 10¹⁰ ds^-1
(B) 1 rutherford = 10⁶ ds^-1
(C) 1 becquerel = 1 ds^-1
(D) 1 fermi = 10³ ds^-1
Answer:
(D) 1 fermi = 10³ ds^-1

Question 18.
Which of the following is the man-made redioactive disintegration series?
(A) Thorium series
(B) Neptunium series
(C) Uranium series
(D) Actinium series
Answer:
(B) Neptunium series

Question 19.
Temperature has no effect on the rate of decay because –
(A) nuclear energies are low
(B) radioactive decay is a statistical process
(C) nuclear energies are very high
(D) radioactive decay follow exponential law
Answer:
(C) nuclear energies are very high

Question 20.
Mark the correct relation-
(A) N₀ = N e ^λt
(B) τ = 1.44 t_0.5
(C) N = N₀ (\(\frac{1}{2}\))ⁿ
(D) t_0.5 = λ ln²
Answer:
(D) t_0.5 = λ ln²

Question 21.
Which one of the following is not a synthetic elements?
(A) U
(B) Cm
(C) Np
(D) PU
Answer:
(A) U

Question 22.
Choose the natural element among the following –
(A) technetium
(B) neptunium
(C) astatine
(D) uranium
Answer:
(D) uranium

Question 23.
Which is not correctly matched here?
(A) Polonium was discovered by Madam curies
(B) Natural radio activity discovered by Henry Becqueral
(C) Maximum penetration power is of α-rays
(D) γ-rays was discovered by willard
Answer:
(C) Maximum penetration power is of α-rays

Question 24.
Positron is the name given to an atom like combination formed between-
(A) a positron and a proton
(B) a positron and a neutron
(C) a positron and α-partical
(D) a positron and an electron
Answer:
(D) a positron and an electron

Question 25.
Which of the following are β – emitters ?
(A) Carbon-14
(B) Cobalt – 60
(C) Tritium – 3
(D) All of these.
Answer:
(D) All of these

Question 26.
Which of the following has highest value for its radioactivity ?
(A) 1 g of Ra
(B) 1 g of Ra so₄
(C) 1 g of Ra Br₂
(D) All of the above have same value
Answer:
(A) 1 g of Ra

Question 27.
Which of the following are α-emitters ?
(A) Helium-5
(B) Tritium
(C) Polonium-212
(D) None of these
Answer:
(C) Polonium-212

Question 28.
In radioactive decay, the emitted electrons come from the-
(A) innermost shell of the atom
(B) outermost shell of the atom
(C) K-shell of an atom
(D) decay neutrons in the nucleus.
Answer:
(D) decay neutrons in the nucleus.

Question 29.
Which emits b-particle?
(A) \({ }_1^3 \mathrm{H}\)
(B) \({ }_6^{14} \mathrm{C}\)
(C) [\({ }_{19}^{40} \mathrm{~K}\)
(D) All of these.
Answer:
(D) All of these.

Question 30.
\({ }_1^3 \mathrm{Al}\) is a stable isotope. It is expected to disintegrate by-
(A) α-emission
(B) β^– -emission
(C) β⁺-emission
(D) proton emission
Answer:
(B) β-emission

Question 31.
Of the following which is not used as a moderator in a nuclear reactor?
(A) Heavy water
(B) Graphite
(C) Beryllium
(D) Sodium
Answer:
(D) Sodium

Question 32.
Control rods used in the nuclear reactor are made of-
(A) nickel
(B) graphite
(C) iron
(D) cadmium
Answer:
(D) cadmium

Question 33.
The moderator used in atomic pile is-
(A) heavy water
(B) uranium
(C) cadmium
(D) iron
Answer:
(A) heavy water

Question 34.
Control rods of nuclear reactor are made up of-
(A) Cd
(B) copper
(C) diamond
(D) graplite
Answer:
(A) Cd

Question 35.
In a nuclear reactor, heavy water is used-
(A) to provide high speed neutrons
(B) to increase the speed of neutrons
(C) to capture neutrons produced by nuclear fission
(D) to transfer the heat from the nuclear reactor
Answer:
(D) to transfer the heat from the nuclear reactor

Question 36.
Near nuclear reactor there is-
(A) large neutron flux
(B) large proton flux
(C) large γ-ray flux
(D) large particles flux
Answer:
(A) large neutron flux

Question 37.
Which of the following isotopes is used in establishing the reaction mechanism of photosynthesis in plants?
(A) \({ }_6^{12} \mathrm{C}\)
(B) \({ }_6^{13} \mathrm{C}\)
(C) \({ }_6^{14} \mathrm{C}\)
(D) \({ }_1^{2} \mathrm{H}\)
Answer:
(C) \({ }_6^{14} \mathrm{C}\)

Question 38.
Which of the following radioactive elements is soluble in water?
(A) Radium
(B) Radon
(C) Technetium
(D) Tritium
Answer:
(B) Radon

Question 39.
Decrease in atomic number is not observed during-
(A) α-emission
(B) β-emission
(C) positron
(D) electron capture
Answer:
(B) β-emission

Question 40.
The relative penetrating power of α, β, γ and neutron (n) follows the order-
(A) α > β > γ > n
(B) n > γ > β > α
(C) β > α > n > γ
(D) None of these
Answer:
(B) n > γ > β > α

Question 41.
Which of the following nuclear reactions will generate an isotope?
(A) Neutron particle emission
(B) Positron emission
(C) α-particle emission
(D) β-particle emission
Answer:
(A) Neutron particle emission

Question 42.
Identify the nuclear reaction that differs from the rest-
(A) positron emission
(B) K-capture
(C) β-decay
(D) γ-decay
Answer:
(D) γ-decay

Question 43.
What is the order of reaction of the decay of ²³5{ _{92 U ?
(A) Zero
(B) first
(C) second
(D) third
Answer:
(B) first

Question 44.
Which of the following has maximum n / P ratio ?
(A) \({ }^{16} \mathrm{Ne}\)
(B) \({ }^{16} \mathrm{O}\)
(C) \({ }^{16} \mathrm{F}\)
(D) \({ }^{16} \mathrm{N}\)
Answer:
(D) \({ }^{16} \mathrm{N}\)

Question 45.
The half life of a radio isotope depends upon-
(A) the amount of isotope
(B) the temperature
(C) the pressure
(D) none of the above
Answer:
(D) none of the above

Question 46.
Which of the following has magic number of protons and neutrons?
(A) \({ }_8^{17} \mathrm{O}\)
(B) \({ }_13^{27} \mathrm{Al}\)
(C) \({ }_9^{17} \mathrm{Al}\)
(D) \({ }_40^{40} \mathrm{Al}\)
Answer:
(D) \({ }_40^{40} \mathrm{Al}\)

Question 47.
India conducted an underground nuclear test at-
(A) Tarapur
(B) Narora
(C) Pokhran
(D) Pushkar
Answer:
(D) Pokhran

Question 48.
Positron has mass equal to –
(A) eletron
(B) α-particle
(C) proton
(D) deutron
Answer:
(A) elecron

Question 49.
\({ }_1^1 \mathrm{H}\) + \({ }_1^3 \mathrm{H}\) (B) \({ }_2^4 \mathrm{He}\) represents –
(A) β-decay
(B) fusion
(C) fission
(D) d-decay
Answer:
(B) fusion

Question 50.
Choose the element which is not radioactive-
(A) Cm
(B) No
(C) Mo
(D) Md
Answer:
(C) Mo

Question 51.
Who discovered radioactivity :
(A) Bacquerel
(B) Madam curie
(c) Peary curie
(D) Ruther ford
Answer:
(A) Bacquerel

Question 52.
Which of the following rays has higher penetrating power ?
(A) sun ray
(B) β-ray
(c) α-ray
(D) γ-ray
Answer:
(D) γ-ray

Question 53.
Which ray is negatively charged ?
(A) α-ray
(B) β-ray
(C) γ-ray
(D) x-ray
Answer:
(B) β-ray

Question 54.
Due to emission of a β-particle the mass of the daughter element :
(A) Increased by one unit
(B) Decreased by one unit
(C) Remains the same
(D) Decreased by two unit
Answer:
(C) Remains the same

Question 55.
Binding energy is :
(A) Bonding between two atoms
(B) Fission of a covalent bond
(C) Binding among the nucleons in nucleus
(D) None of these
Answer:
(C) Binding among the nucleons in nucleus

Question 56.
Nuclear fission is initiated by :
(A) slow neutron
(B) fast neutron
(C) by proton
(D) by α-particle
Answer:
(A) slow neutron

Question 57.
Nuclear energy is :
(A) renewable
(B) not renewable
(C) sometime renewable
(D) it is a matter of debate
Answer:
(B) not renewable

Question 58.
The radioactive isotope used in atom bomb is :
(A) Ra-226
(B) U-238
(C) C-14
(D) U-235
Answer:
(D) U-235

Question 59.
Source of energy of sun is :
(A) Fission reaction
(B) Fusion reaction
(C) Spalation reaction
(D) None of these
Answer:
(B) Fusion reaction

Question 60.
Which nuclear decay emission consists of energy only?
(A) alpha particle
(B) beta particle
(C) gamma radiation
(D) positron emission
Answer:
(C) gamma radiation

Question 61.
Which of the following is the correct order of ionising power for α β, and γ ravs?
(A) α > β > γ
(B) α > γ > β
(C) γ > β > α
(D) β > α > γ
Answer:
(A) α > β > γ

Question 62.
Electromagnetic wave among the radloactive rays is :
(A) α-rays
(B) β-rays
(C) γ-rays
(D) cathode rays
Answer:
(c) γ-rays

Question 63.
Which one among the following nuclet has the lowest n:p ratio?
(A) Hydrogen
(B) Deuterium
(C) Tritium
(D) Helium
Answer:
(A) Hydrogen

Question 64.
Number of neutrons in a α-particle is :
(A) 1
(B) 2
(C) 3
(D) 4
Answer:
(B) 2

Question 65.
Identify the wrong statement :
(A) Radioactivity is a nuclear phenomena
(B) Emission of radioactive rays depends on the number of valence electrons
(C) Radioactivity was first discovered by Becquerel
(D) Three types of radiations are emitted during radiation from a radioactive element.
Answer:
(B) Emission of radioactive rays depends on the number of valence electrons.

Question 66.
Atom bomb was first used in war during
(A) World war II
(B) Gulf war
(C) Cuban war
(D) Indo-Pak war in 1965
Answer:
(A) World war II

Question 67.
Nuclear fission is initiated by :
(A) slow neutron
(B) proton
(C) fast neutron
(D) α particle
Answer:
(A) slow neutron

Question 68.
At around what mass number is the binding energy per nucleon greatest?
(A) 26
(B) 58
(C) 111
(D) 235
Answer:
(B) 58

Question 69.
The nuclear reaction \({ }_1^2 \mathrm{H}\) + \({ }_1^2 \mathrm{H}\) → \({ }_2^4 \mathrm{He}\) is called :
(A) fission reaction
(B) fusion reaction
(C) chain reaction
(D) thermal reaction
Answer:
(B) fusion reaction

Fill in the blanks :

1. Due to the large mass, a-particles possess large ______.
Answer:
Kinetic energy.

2. β-particles are _______ charged.
Answer:
negatively

3. γ-rays are _______.
Answer:
neutral

4. γ-rays have least effect on _______.
Answer:
photographic plates

5. Isotopes of the same element possess same number of _____.
Answer:
protons

6. Accroding to Einstein’s equation, the relationship between mass and energy can be written as ______.
Answer:
E = m c²

7. Atoms of the same element having same atomic number but different atomic masses are called ______.
Answer:
isotopes

8. Atoms of the different elements paossessing same mass number are called _____.
Answer:
Isobars.

9. Isotones are the nuclides having same number of ______.
Answer:
neutrons.

10. Atoms of the same element possessing identical atomic mass but differing in half-life period are called ______.
Answer:
nuclear isomers.

11. The phenomenon of spontaneous emission of invisible radiation is called ______
Answer:
radioactivity

12. β-particles are nothing but ______ moving with high speeds.
Answer:
electrons

13. Electrically neutral electromagnetic waves ejected during radioactive disintegration are called ______.
Answer:
γ-rays.

14. The phenomenon in which a stable nuclide is converted artificially into a radioactive substance is called _____.
Answer:
artificial radioactivity.

15. The speed of γ-rays is ______ speed of light.
Answer:
equal to

16. Atom bomb is based on nuclear _______ reaction.
Answer:
fission

17. Hydrogen bomb is based on nuclear _______ reaction.
Answer:
fusion

18. Source of the energy of the Sun is ______.
Answer:
fusion

19. The time taken for decay of half the initial amount of a radioactive nuclide is called _____.
Answer:
half-life period.

20. The energy required to separate a nucleus into its individual nucleons is known as _______.
Answer:
binding energy

21. The number of neutrons in a radioactive isotope of hydrogen is _____.
Answer:
2

22. The rate of disintegration of active nucleus is known as ______.
Answer:activity

23. \({ }_1^2 \mathrm{H}+{ }_1^3 \mathrm{H} \rightarrow{ }_2^4 \mathrm{He}\) is a _____ reaction.
Answer:
fusion

24. The mass defect in the formation of boron atom \(\frac{1}{5}\) B is 0.0810 amu. The binding energy per nucleon is ______.
Answer:
6.86 MeV

25. \({ }_7^{14} \mathrm{~N}+{ }_0^1 \mathrm{n}\) → ________ + \({ }_7^{14} \mathrm{H}\)
Answer:
{ _6^{-14 C

26. A radioactive nucleus decay emitting one α and two β particles, the daughter nucleus is _______ of the parent.
Answer:
isotope.

27. Particles having energy of several hundred MeV are known as _______.
Answer:
Superfast particles

28. An element \({ }_{\mathbf{Z}}^{\mathbf{A}} \mathbf{M}\) undergoes α-emission followed by two successive β-emissions. The element formed is _______.
Answer:
\(\mathrm{A}_z^{-4} \mathrm{M}\)

29. The end products in the natural disintegration series are stable isotopes of _____.
Answer:
lead

30. One curie of activity is equal to _______ disintegrations per second.
Answer:
3.7 × 10¹⁰

31. The energy equivalent to 1 amu is ______ MeV.
Answer:
931.5

32. The density of the nucleus is of the order of ______ g/cm³.
Answer:
10¹⁴

33. The difference between the total mass of the particles present in the nucleus of a nuclide and its real mass is called ______.
Answer:
mass defect

34. In exoergic reaction, the total mass of the products is _______ than the total mass of the reactants.
Answer:
less.

35. _______ is the inventor of neutron.
Answer:
J. Chadwick.

36. N₂O and CO₂ are the examples of ________.
Answer:
isosters

37. Magic numbers are 2, 8, 20, 50, 82 and ______.
Answer:
126

38. Radioactivity was proposed by ______.
Answer:
Madam curie.

39. Measurement of radioactivity is done by ______.
Answer:
Geiger-Muller counter.

40. The process of transforming one element into other is known as _______.
Answer:
alchemy.

41. Radioactivity was discovered by _______.
Answer:
Becquerel

42. Charge of an α-particle is _______.
Answer:
+2

43. β – particles are emitted from the _______ of the atom.
Answer:
nucleus.

44. \({ }^{60} \mathrm{C}_0\) isotope is used for the treatment of ______.
Answer:
cancer

45. \({ }^{226}{ }_{8 R} R a\) is a _______ element.
Answer:
radioactive

46. Bombardment of one U-235 with one neutron producer ______ neutrons.
Answer:
3

47. chernobyl located in _______.
Answer:
ukraine

48. One gram U-235 generates ________ kW/h electric energy.
Answer:
20,000

49. Fusion reaction occurs at _______ temperature.
Answer:
10⁶ K.

50. The inert gas present in each series is ________.
Answer:
Radon

51. The first radioactive element discovered was __________.
Answer:
uranium

52. In transformation series, radioactivity finally ceases with a a stable __________ isotope as the end product.
Answer:
lead

53. __________ is preceded by a fission reaction.
Answer:
Fusion

54. In a nuclear reactor, the part which consists of the moderator and fuel rods is known as _________.
Answer:
reactor core

55. ‘Atom bomb’ utilizes the ___________ reaction.
Answer:
fission

56. According to theory of relativity, mass can be converted to __________ and vice versa.
Answer:
energy

57. Natural uranium with extra U-235 added into it is called ___________.
Answer:
enriched uranium

58. The name of the aeroplane which dropped atom bomb on Hiroshima is ___________.
Answer:
Enola Gay

Q59. On an average ____________ neutrons are produced per each fission.
Answer:
2.5

State whether the following statement is True or False : VSA

1. Radioactivity depends on the number of electrons in the valence shell.
Answer:
False

2. The instability of nucleus in radioactive atoms is caused by the ratio of neutrons and protons in the nucleus.
Answer:
True

3. Radioactivity is a nuclear phenomena.
Answer:
True

4. Due to emission of a beta particle, mass number of the daughter element is decreased by 1 unit.
Answer:
False

5. When metallic radium is converted to radium chloride, it shows a change in the property of radioactivity.
Answer:
False

6. Radioactive tracer technique is used by researchers and medical practitioners.
Answer:
True

7. Fusion is basically just opposite to fission.
Answer:
True

8. Binding energy owes its origin to mass defect.
Answer:
True

9. Fission reaction releases a large amount of energy.
Answer:
True

10. Inside the thermal reactor, the control rods slow down the neutrons to stimulate further fission.
Answer:
False

11. Nuclear reactor is used to safely convert nuclear energy into electricity.
Answer:
True

12. Atom bomb is based on principles of thermonuclear fusion.
Answer:
False

13. Energy of the stars is attributed to nuclear fission reactions.
Answer:
False

14. The nuclear disaster in Fukushima was initiated after a Tsunami.
Answer:
True

Comprehensive WBBSE Class 10 Physical Science Notes Chapter 4 Thermal Phenomena can help students make connections between concepts.

Thermal Phenomena Class 10 WBBSE Notes

Heat: It is a form of energy which produces sensation of warmth.

Different types of motion:

• Translational motion: Motion along a straight line.
• Vibrational motion: Motion of the molecules about a mean position.
• Rotational motion: Rotation of the molecules about their axes.

Definition of heat with respect to motion: Heat possessed by a body is the total thermal energy of the body and is the sum of kinetic energies of all the individual molecules forming the body due to translational, vibrational and rotational motions of the molecules.

Unit of heat:

• CGS : Calorie
• SI : Joule

One calorie : It is the quantity of heat required to raise the temperature of 1 g water through 1°C

Relation between calorie and Joule : 1 Calorie = 4.18 Joule

Temperature : It is the thermal condition of a body which would determine the direction of flow of heat, when the body is placed in thermal contact with another body.

Measurement of Temperature: Temperatures are measured with a thermometer.

Upper fixed point: It is the temperature of steam from water boiling under a pressure of 76 cm of mercury at sea level and 45° latitude.

Lower fixed point: It is the temperature of melting ice under the same conditions.

Fundamental Internal: The difference between the fixed points of a scale is called fundamental internal.

Different scales of temperature commonly used:

• Celsius scale (by Anders celsius, 1710 , upper fixed point 100°C and Lower fixed point 0°C)
• Fahrenheit scale (by Gabriel Fahrenheit, 1717, upper fixed point = 212° Fand lower fixed point 32°F).
• Absolute or Kelvin scale.

Relation between Celsius and Fahrenheet scale:

\(\frac{C}{5}=\frac{F-32}{9}\)

Relation between Celsius and Kelvin scale :

C = K-273.15

Thermal Expansion : Dimensions of all substances generally increases with increase in temperature. This phenomenon is known as thermal expansion.

Types of expansions in solids:

• Linear expansions
• Superficial expansions
• Volume expansions

Coefficient of linear expansion: The coefficient of linear expansion may be defined as the fractional increase in length of a solid per degree rise in temperature.

[α = \(\frac{l_2-l_2}{l_1\left(t_2-t_1\right)}\)]

[l₁ and l₂ are the lengths of a bar at temperatures t₁ and t₂° respectively, α = coefficient of linear expansion]

Coefficient of Superficial Expansion: The co-efficient of superficial or surface expansion of a solid is defined as the fractional change in surface area of the solid per degree rise in temperature.

[β = \(\frac{s_2-s_1}{s_1\left(t_2-t_1\right)}\)]

[s₁. and s₂ are the surface areas of a solid at t₁° and t₂° respectively, β = coefficient of superficial expansion]

Coefficient of cubical expansion: The coefficient of cubical or volume expansion of a solid is defined as the fractional increase in volume of the solid per degree rise in temperature.

[γ = \(\frac{v_2-v_1}{v_1\left(t_2-t_1\right)}\)]

[v₁. and v₂ are the volumes of a solid t₁° and t₂° respectively, γ = coefficient of superficial expansion]

Coefficient	Unit	Dimension
α	K-1 or °C-1 or °F-1	l-1
β	K-1 or °C-1 or °F-1	l-1
γ	K-1 or °C-1 or °F-1	l-1

Relation among α, β and γ : \(\left[\alpha=\frac{\beta}{2}=\frac{\gamma}{3}\right]\)

Various applications of solids in our daily life:

• Thermostat Fire Alarm
• Bimetallic Thermometer
• Compensating Rod Type Pendulum
• Harrison’s Grid-iron Pendulum

Apparent expansion of the liquid: If the expansion of the liquid is measured ignoring the expansion of the containing vessel, the expansion is called the apparent expansion of the liquid.

Real expansion of the liquid: When the actual expansion of the liquid is measured by considering the expansion of the containing vessel, it is called real expansion of the liquid.

Real expansion of the liquid = expansion of the vessel + apparent expansion of the liquid

Co-efficient of real expansion of liquids: The coefficient of real or absolute expansion of a liquid is the fraction of its volume

γ_r = \(\frac{v_2-v_1}{v_1\left(t_2-t_1\right)}\)

(v₁ is the initial volume of a given mass of a liquid at t₁° and v₂ is the real volume of the same mass of the liquid at t₂°, γ_r is the coefficient of real expansion of the liquid).

Co-efficient of apparent expansion of liquids: The coefficient of apparent expansion of the liquid is the traction of its volume by which the liquid appears to expand per degree rise in temperature.

[γ_r = \(\frac{v_2-v_1}{v_1\left(t_2-t_1\right)}\)]

(v₂ is the apparent volume of the liquid at t₂°, γ_a is the coefficient of apparent expansion of the liquid).

Relation between expansion coefficients of a liquid:

(γ_r. is the coefficient of real expansion of the liquid, γ_a is the coefficient of apparent expansion of the liquid). γ_s is the coefficient of cubic expansion of the material of the vessel)

γ_r = \(\frac{v_2^{\prime}-v_1}{v_1\left(t_2-t_1\right)}\)

Variation of density of a liquid with temperature: Let m mass of a liquid has volumes v₁ and v₂ at temperatures t₁° and t₂° respectively. If ρ₁ and ρ₂ be the densities of the liquid at t₁° and t₂° respectively and if γ_r, be the coefficient of real expansion of the liquid then,

When a liquid is more expansible than the material of the vessel, there will be, on the whole, an apparent expansion of the liquid. In the reverse case, the liquid will apparently cantact. If two expand equally, the volume of the liquid will appears to remain constant.

A hollow vessel expands as if it were solid having the same volumes, because if the hollow of the vessel were also solid, after expansion it would fit in with outer vessel.

Anomalouis expansion of water: Usually liquids expand on heating. But in the case of water we find deviation from this general behaviour of the liquids within a certain range of temperature. The volume of water is minimum at 4°C and hence its density is maximum at 4°C. This phenomenon is called the anomalous expansion of water.

Conclusion of Hope’s experiment: From Hope’s experiment it is proved that water at bottom which is denset is at 4°C. After sufficiently long time the temperature of the lower thermometer falls slightly due to loss of heat by conduction to the upper regions.

Effect on Marine life: Anomalous expansion of water has great practical importance on the marine life in the cold countries. The temperature of the deeper layers of the water in the pond remains nearly at 4°C and falls gradually at 0°C upwards till the layer of ice is reached. The marine life in the water is thus saved. For the same reason temperature of the bottom of a deep sea remains constant (i.e. 4°C ) throughout the year.

Expansion of a gas at constant Temperature:

Boyle’s Law: The volume of a fixed mass of a gas of constant temperature is inversely proportional to its pressure.

V ∝ \(\frac{1}{P}\) (At constant temperature P is the pressure and V is the volume of a fixed mass of gas)
or V ∝ \(\frac{K}{P}\) (K is the proportionality constant. It depends
or, PV = K = constant

• the mass of the gas
• nature of the gas
• temperature of the gas)

Expansion of a Gas at constant Pressure :

Charles’ Law: The pressure remaining constant, the volume of a given mass of any gas increases (or decreases) by the constant fraction \(\frac{1}{273}\)of its volume of 0°C, for every degree celsius increase (or decrease) of temperature.

V_t = V₀(1 ± \(\frac{t}{273}\))
v₀ and v_t are the volumes of a given mass of gas at 0°C and t°C respectively, the pressure of the gas remaining constant all through)

Expansion of gas at constant volume:

Pressure Law: Volume remaining constant, the pressure of a given mass of a gas increases (or decreases) by a constant fraction \(\frac{1}{273}\)of its pressure at 0°C for each degree celsius increase (or decrease) of temperature.

P_t = P₀(1 ± \(\frac{t}{273}\))

(P₀ and P_t are the pressures of a given mass of gas at 0°C and t°C respectively, the volume of the gas remaining constant all through)

Volume Coefficient (γ_p) : The volume coefficient of a gas is the fractional increase in the volume of the gas at 0°C for each degree celsius rise in temperature, the pressure remaining constant.

V_t = V₀(1 + γ_p t)

From Charles’ Law, we find γ_p = \(\frac{1}{273}\)°C^-1 = 36.6 × 10_-4 °C^-1

Pressure Coefficient (γ_ν): The pressure coefficient of a gas is the fractional increase in pressure of the gas at 0°C for each degree celsius rise in temperature, the volume remaining constant

P₁ = P₀(1 + γ_v t)

From Pressure law, we find that γ_v = \(\frac{1}{273}\)°C^-1 = 36.6 × 10_-4 °C^-1

Equality of volume and pressure coefficients : Consider a given mass of a gas at °C having pressure and volume P₀ and V₀ respectively. It is heated to a temperature t°C in two alternative ways viz (I) at constant volume, when pressure changes to a P_t or (II) at constant pressure, when the volume changes to V_t.

In the case I, Pressure Law’s is applicable,

so P_t = P₀(1 + γ_v t)

In case II, Charle’s law is applicable, so V_t = V₀(1 + γ_v t)

In both the cases final temperature is t°C and so according to Boyle’s Law

P_t V₀ = P₀ V_t
or, P₀ V₀(1 + γ_v t) = P₀ V₀(1 + γ_{p</sub t)
∴ γv = γr}

Ideal gas and Ideal gas equation: A gas which obeys gas laws is called. A gas which obeys gas laws is called an ideal gas. An ideal gas equation is PV = nRT (R = universal gas constant)

Speciefic heat capacity: Specific heat capacity of a substance is the amount of heat required to rise the temperature of unit mass of the substance through one degree.

Specific heat of water:

• 1 cal g^-1 °C^-1 : CGS system
• 4200 Jkg^-1 K^-1 : SI system.

Molar specific heat capacity: Molar specific heat capacity of a substance is the amount of heat required to raise the temperature of one gram mole of the substance through a unit degree.

Molar specific heat at constant volume (C_v) : The molar specific heat of a gas at constant volume (C_v) is the amount of heat required to raise the temperature of one mole of the gas through one degree keeping the volume constant throughout.

Molar specific heat at constant pressue (C_p) : The molar specific heat of a gas at constant pressure (Cp) is the amount of heat required to raise the temperature of one mole of the gas through one degree keeping the pressure constant throughout.

C_p is greater than C_v

Thermal capacity: Thermal capacity of a substance is the quantity of heat required to raise the temperature of it by 1°.

Water equivalent: Water equivalent of a body is the mass of water which will be heated through 1° by the amount of heat that raises the temperature of the body through 1°.

Fundamental principle of calorimetry
Heat lost by hot body = Heat gained by cold body.

Conditions :

during the process of heat thransfer, there is no heat exchange with the surrounding.
No chemical reaction takes place between the bodies. This is known as fundamental principle of calorimetry.

Latent heat of substance: The amount of heat to be supplied or extracted for changing completely the stake of unit mass of a substance without change of temperature is called the latent heat of the substance for the corresponding change of state.

Melting point and effect of pressure on it :

Melting point: The normal melting point of a solid is the definite temperature at which it melts on heating under normal atmospheric pressure and the temperature remains constant until the melting is complete.

Regelation: The phenomenon of melting of ice under pressure and freezing again on releasing the pressure is called regelation.

Bioling point and e effect of pressure on it:

Bolling point: The normal boiling point of a liquid in the temperature at which a liquid boils under normal atmospheric pressure.

The boiling point of a liquid depends uy on:

• the nature of the liquid
• presence of dissolved substance
• the superincumbent pressure.

Vapour pressure: Whenever a liquid evaporates at any temperature, the vapour exerts a definite pressure on everything in contact. This pressure is called vapour pressure of the liquid at that temperature.

Saturated vapour: If the liquid be allowed to evaporate in a closed space, it is found that after a small time evaporation stops, i.e., t a given temperature, there is a maximum limit to the amount of vapour the space can hold. The space is said to be then saturated with vapour and the vapour is then called saturated vapour.

Difference between Gas and Vapour-Critical Temperature: For every substance in gaseous state there is a certain temperature such that if the substance be below this temperature, it can be liquefied by the application of suitable pressure, and if above this temperature, it cannot be liquified, however large the pressure may be, then the temperature is called the critical temperature for that substance.

Thus a gaseous substance at a temperature above critical temperature is called gas and when it is at a temperature below its critical temperature it is called vapour.

Thermal conduction

Conduction: Conduction is the process of transfer of heat through a substance without any detectable motion of the particles of the substance.

Good conductors: The substances through which heat is conducted easily from one region to the other are called good conductors.

Bad conductors or Insulators: The substances through which heat is not conducted easily from one region to the other are called bad conductors or insulators.

Coefficient of thermal conductivity: The coefficient of thermai conductivity at the material of a substance is numerically equal to the quantity of heat that conducts in one second normally through a slab of unit length and unit area, the difference of temperature between its end faces being one degree.

Unit of thermal conductivity

CGS: Cal cm^-1 S^-10 C^-1
SI: Jm^-1 S^-1 K^-1 or Wm^-1 k^-1
Dimension: [MLT^-3 θ^-1]

Thermometric conductivity: The rate of rise of temperature during the variable state is proportional to K / P₃ (where K = thermal conductivity of the material, P_s = specific heat). This ratio is known as thermometric conductivity or the thermal conductivity per thermal capacity per unit volume.

Unit of thermometric conductivity:

CGS: cm² s^-1 ; SI: m² s^-1

Dimension of thermometric conductivity: [M⁰ L² T^-1]

Although thermal conductivity of iron is more than that of lead, diffusivity of lead is more and they under similar conditions of heat flow, the temperature of different sections of the lead bar would rise more rapidly than iron bar.

Applications of conductivity:

ICE is packed in saw dust, because air which is bad conductors of heat being trapped in the saw dust prevents transfer of heat from the surrounding to the ice. So ice does not melt.

Cooking utensils are provided with wooden or plastic handles, as wood or plastic are bad conductors of heat, so we can hold the hot utensils with the help of these handles.

Wearing two cotton shirts of half the thickness each is better than a single shirt of double the thickness in winter. There is a layer of bad conductor air entrapped between the two shirts providing additional protection from heat conduction from the body.

In winter, birds often swell their feathers, thereby enclosing air between their bodies and feathers and thus does not allow flow of heat from the bodies of the birds and keeps them warm.

Convection of Heat: Convection is the process by which heat is transmitted through a liquid or gas from a hotter point to a colder point due to the bodily motion of the heated particles of the substances.

It may be noted that although mercury is a liquid, it is heated by conduction and not by canvection.

Radiation: Radiation is the transmission of heat from a hot body to a cold body without the help of any medium and without appreciable heating of the intervening medium if any.

Some basic characteristics of thermal radiations are:

• (i) They travel along straight line with velocity of light.
• They require no medium for their propagation and even if there be intervening medium, the medium is not affected.
• They obey inverse square law i.e. their intensity varies inversely as the square of the distance from the source.
• They can be reflected and refracted like light.
• They also exhibit the phenomena of interference, diffraction and polarisation.

The reflecting power of a body (Reflectance) : It is the ratio of the amount of thermal radiations reflected by the body in a given time to the total amount of thermal radiation incident on the body in the same time.

The absorbing power of a body (absorbtance): It is the ratio of the amount of thermal radiations absorbed by the body in a given time to the total amount of thermal radiations incident on the body in the same time.

The transmitting power of a body (transmittance): It is the ratio of the amount of thermal radiations transmitted through the body in a given time to the total amount of thermal radiations incident on the body in the same time.

Perfectly Black body; A perfectly black body is that which absorbs completely the radiations of all the wavelengths on it.

Kirchoff’s Law : It states that the ratio of emissive power to absortive power corresponding to a particular wavelength and at any given temperature is always a constant for all bodies, the constant being equal to the emissive power of a perfectly black body at the same temperature and corresponding to the same wavelength.

Stefan’s Law: It state that the amount of heat energy emitted per second by unit area of a perfectly black body is directly proportional to the fourth power of absolute temperature of the body.

Wen’s displacement Law: It states that the wavelength of maximum intensity of emission of black body radiation is inversely proportional to the absolute temperature of the body.

Newton’s Law of cooling: It states that the rate of loss of heat of a liquid is directly proportional to the difference in temperatures at the liquid and the surroundings, provided the difference in temperature is small.

Green house effect: Green house effect is an example of selective absorption of heat by glass. The amount of heat transmitted through a substance depends on temperature of the source of heat.

Global warming: CO₂, water vapour, methane, nitrous oxide, tropospheric ozone, chlorofluoro carbon compounds, halogen compounds etc. on increasing the amount of green house gases in the atmosphere, the temperature of earth.

Effect of global warming:

• Possibility of increasing the sea level
• Effect on atmosphere
• Effect on forest and agriculture

Comprehensive WBBSE Class 10 Physical Science Notes Chapter 8.1 Periodic Table and Periodicity of the Properties of Elements can help students make connections between concepts.

Periodic Table and Periodicity of the Properties of Elements Class 10 WBBSE Notes

Classification: It is the method of arranging similar elements together and separating them from dissimilar elements.

(i) Law of triads (Dobereiner, 1817) : In a triad of elements having similar properties, the atomic weight of the central element was merely the arithmetic mean of the atomic weights of the other two elements. e.g. Li (At. wt. = 6-94), Na (At. wt. = 23), (At. wt.= 39-1)
Atomic weight of\(\mathrm{Na}=\frac{6.94+39.1}{2}=23.02\) (which is nearest value of 23.)

(ii) Law of Octave : (J.A.R. Newlands, 1864) : The elements when arranged in the increasing order of their atomic weights, the eight succeeding element was the repetion of the first one like the 8th note of the musical scale.

(iii) Lother Meyer curve : Lother Meyer plotted a graph between atomic volumes of elements and their atomic weights. He found that similar elements occupied similar positions of the curve.

(iv) Mendeleef’s Periodle Laws (Mendeleef, a Russian Chemist in 1896): It states that the physical and chemical properties of the elements are the periodic function of their atomic weights.

Mendeleef’s periodic table :

• Periodic table : When the elements are arranged in their increasing order of atomic weight in seven periods and nine groups, the total distribution or chart, that is obtained is called periodic table.
• Period : The horizontal rows in a periodic table are known as periods. At present the periodic tabic contains seven periods.
• Group : The vertical columns of the periodic table are known as groups. The present Mendeleef’s periodc table has nine groups. The groups in periodic table-form the first group to the eight group are designated by roman number 1, II, III, IV, V, VI, VII and VIII. The ninth group is designaged by ‘O’ number.

• Sub-group : Except group ‘VIII’ and ‘O’ each group from I to VII has two sub-groups-A and B. As a result, H find Li, Na, K, Rb, Css, Fr place in IA sub-group and Cu, Ag, Au find place in sub-group IB. In a similar way, the sub-group VIIA contains Mn, Te, Re while F- Cl, Br, I, At are included in sub group VIIB.

• The elements when arranged in this manner were found that elements of the same sub-group show similarity in properties.

• Modern Periodic Law : (Moseley, 1913-14) : It states that the physical and chemical properties of the elements are the periodic function of their atomic numbers.

• Periodicity : It is the recurrence of elements with similar properties after certain regular intervals when these elements are arranged in the increasing order of their atomic numbers.

• Cause of periodicity; It is the recurrence of similar electronic configuration.

Long form periodic table Rohr’s table) : It is based on the modern periodic law. It has eighteen vertical columns or groups and seven horizontal rows of periods. The periodic table can be divided into four main regions according to whether the s, p, d or f levels are being filled

Period	Fill orbitjil in period	No. of elements present in period
1st Period	Is	2
2nd Period	2s- 2p	(2 + 6) = 8
3rd Period	3s 3p	(2 + 6) = 8
4th Period	3s 3d 4p	(2 + 10 + 6) = 18
5th Period	5s 4d 4p	(2 + 10 + 6) = 18
6th Period	6s 4f 5d 6p	(2 + 14 + 10 + 6) = 32
7th Period	7s 5f 6d	(2 + 14 + 10) = 26
(incomplete)		(Incomplete)

N.B, The elements with atomic numbers (58-7) and (90-103) are called lanthanoids and actinoids respectively. Elements from 93 onwards are purely synthestic and are called trans-uranium elements. These are radioactive in nature.

• The groups are denoted by IA to VIIA, IB to VIIB, VIII (There columns) and The elements in which the last added electron goes to s or p sub-levels are placed in A sub-groups, while those in which it goes to d or f sub-levels are placed in B-sub-groups. In accordance with the 1984, IUPAC recommendations the groups are numbered (1-18) and this notation replaces the old numbering scheme.

• The relationship between odd and new notations is as follows :

Old	IIA	IIIB	IVB	VB	VIB	VIIB	VIII	IB	IIB	IIIA-VIIA	Zero(O)
New	2	3	4	5	6	7	8-10	11	12	13-17	18

Division of elements into s, p, d, f blocks :
s-block elements : These are the elements of IA or 1 group (alkali metal; outermost electronic configuration ; ns¹) and IIA or 2 group (alkaline earth metals, outermost electronic configuration : ns² ) These are so named because the last electron in them enters s-orbitals.

Characteristics of s-block elements :

• These are soft metals having low melting point and boiling point.
• These have low ionisation energies.
• These are highly reactive and readily from univalent or bivalent positive
• The metals and their salts give characteristic colours of the flame.
• In the molten state or solution form these are good conductors of heat and
• These are good reducing agents due to their low ionisation energies.
• The hydroxides of s-block elements are strong bases.

(b) p-block elements : The last electron enters p-orbital of the valence shell of p-block elements. The elements with configurations ns²np¹ to ns²np⁶ constitute this block. Thus, p-block consists of elements of group IIIA (13), IVA(14),VA(15), VIA(16), VIIA (17) and zero group 18. Their (n-1) s, p and orbitals are fully filled. Thus, only the outermost orbitals in these elements are incomplete.

Characteristics of p-block elements :

• They include both metals and non-metals.
• They have quite high ionisation energies.
• They form mostly covalent compounds.
• In a period, these are gradation from reducing to exidising properties.
• Generally bad conductors to heat and electricity.
• Atomic radii decrease across a period and increase down a group.
• Heavier elements exhibit variable valency.

(c) d-block elements : The last electron enters a (n-1)d orbital. These have configurations
(n-1)d^1–10ns^0–2. This block is present in between s and p-block elements d-block elements are also known as transition elements.

Characteristics of d-block elements :

• All these elements are metals and have high melting and biding points.
• These are good counductors of heat and electricity.
• They show variable oxidation states.
• They generally form coloured compounds.
• d-block elements have a strong tendency to form complexes.
• They are used as catalyst.

(d) f-block elements : The last electron enters a (n-2) f -orbital. Lanthanoids and actinoids constitute the f-block and are also shown separately at the bottom of the periodic table.

They have (n-2)f ^1-14(n-1)d^1-10 ns² configuration.
They are also known as inner trasition elements. Elements in which the last electron enters 4f-orbitals are known as lanthanides or lanthanoids (Atomic

Number 58 to 71) and elesments in which the last electron enters a 5f-orbitals are known as actinides or actinoids (Atomic number 90 to 103). Characteristics of f-block elements :

• They are heavy metals having high melting and boiling points.
• f-block elements show variable valency.
• They form coloured ions.
• They are paramagnetic due to the presence of unpaired electrons.
• Actinides are radioactive in nature.

Periodic properties and their variations in periodic and group :
(i) Atomic size : The distance of the outermost orbit from the nucleus of spherically shaped atom is called the atomic size.

Atomic size decreases across a period due to increase in nuclear change and increases down a group due to the successive addition of new shells,

(ii) Metallic and non-metallic character : Metallic character decreases and non-metallic character increases across a period and metallic character increases and non-metallic character decreases down a group

(iii) Electronegativity : It is the relative tendency of an element in a molecule to attract the shared pair of electrons towards itself. It increases across a period due to increase in nuclear charge and decreases down a group owing to increase in atomic size and shielding of inner electron shells, e.g. Period 2 :

(iv) Ionisation energy (I.E.) It is the amount of energy required to remove a valence electron from a neutral gaseous atom.
I.E increases across a period and decreases down a group.

(v) Electron affinity : It is the energy released when an electron is added to a neutral gaseous atom.
Electron affinity increases across a period and decreases down a group.

(vi) Diagonal relationship : Elements of second and third row which are present diagonally have similar properties because on moving along the diagonal, the decrease and increase of size, electropositive character and polarizing power partly cancel each other.

(vii) Oxidising and Reducing Character : Oxidising character of the elements increases across a period and decreases down a group. Conversely, reducing character decreases across a period and increases down a group.

(viii) Density: It increases in a group from top to bottom and in a period, it increases in a regular manner from the left.

(ix) Electronic configuration and poistion in the Periodic Table :

Position of hydrogen in the periodic table :
In the periodic table, hydrogen may find a place either in Group I or Group VII when valency and property are taken in account. The reasons are :

Similarities with Group I elements :

• Hydrogen is monovalent and an electropositive element like the alkali metals.
• On electrolysis of hydrogen associated compounds, hydrogen is liberated at the cathode like an alkali metal.
• Hydrogen is a reducing agent like an alkali metal.
• Hydrogen forms stable oxide (H₂O) like an alkali metal.
• Hydrogen forms compounds with non-metals like an alkali metal.

Similarities with Group VII elements :

• Hydrogen and the halogens have valency 1.
• Hydrogen and the halogens are diatomic gaseous non-metals.
• Hydrogen forms hydrides with metals like the halogens e.g. NaH.

Differences with the alkali meals (Group I) :

• Hydrogen is a non-metal but the Group 1 elements are metals.
• Hydrogen is gas at the ordinary temperature the alkali metals are solid at the ordinary
  temperature (exception : Cs is liquid).
• Hydrogen molecule is diatomic, but the alkali metals are monoatomic.

Differences with the halogen elements (Group VII) :

• Hydrogen is a reducing agent but the halogens are strong oxidising agent.
• In electronic configuration also, hydrogen shows dissimilarity with the halogens. From the above discussion, it is understood that hydrogen may be included in group I and Group VII. So, the actual poistion of hydrogen has not been identified till date. So, hydrogen is called ‘rouge element’.

Well structured WBBSE Class 10 Physical Science MCQ Questions Chapter 3 Chemical Calculations can serve as a valuable review tool before exams.

Chemical Calculations Class 10 WBBSE MCQ Questions

Multiple Choice Questions (MCQ) :

Question 1.
Calcium pyrophosphate is represented by the formula Ca₂ P₂ O₇. The molecular formula of ferric pyrophosphate is :
(A) Fe₂(P₂O₇)₄
(B) Fe₂(P₂O₇)
(C) Fe(P₂O₇)₃
(D) Fe₄(P₂O₇)₃
Answer:
(D) Fe₄(P₂ O₇)₃

Question 2.
The chemical formula of a particular compound represents :
(A) the size of its molecule
(B) the shape of its molecule
(C) the total number of atom in a molecule
(D) the number of different types of atoms in a molecule
Answer:
(D) The number of different types of atoms in a molecule.

Question 3.
The formula which represents the simple ratio of atoms in a compound is called:
(A) empirical formula
(B) molecular formula
(C) structural formula
(D) rational formula
Answer:
(A) Empirical formuia

Question 4.
If 0.5 mole of BaCl₂ is mixed with 0-2 mol of Na₃ PO₄, the maximum number of mol of Ba₃(PO₄)₂ that can be formed is :
(A) 0.7
(B) 0.5
(C) 0.30
(D) 0.10
Answer:
(D) 10

Question 5.
2.76 g of silver carbonate on being strongly heated yields residue weighting
(A) 2.48 g
(B) 2.15 g
(C) 2.32 g
(D) 2.64 g
Answer:
(C): 32 g

Question 6.
27 g of Al will react completely with how many grams of oxygen ?
(A) 8 g
(B) 16 g
(C) 32 g
(D) 24 g
Answer:
(D) 24 g

Question 7.
NH₃ + HCl = NH₄ CI; it is a type of chemical reaction
(A) substitution
(B) direct combination
(C) addition reaction
(D) rearrangement
Answer:
direct combination

Question 8.
N₂ + O₂ = 2 NO-Q Cal ; this reaction is
(A) endothermic
(B) exothermic
(C) rearrangement
(D) decomposition
Answer:
(A) endothermic

Question 9.
Which of the following one takes part in chemical reaction?
(A) electron
(B) proton
(C) ion
(D) positron
Answer:
(A) electron

Question 10.
The reaction in which two or more reactants combine directly forming molecules of new substances is called
(A) decomposition
(B) direct combination
(C) addition reaction
(D) neutralisation reaction.
Answer:
(ii) direct combination

Question 11.
The reaction in which molecule or molecules of a compound break down into comparatively simpler molecules in presence heat or electricity is called.
(A) decomposition
(B) direct combination
C) double decomposition
(D) neutralisation reaction
Answer:
(A) decomposition

Question 12.
The balanced equation for the chemical equation
MnO₂ + HCl → MnCl₂ + Cl₂ + H₂O is :
(A) MnO₂ + 2 HCl = 2 MnCl₂ + Cl₂ + H₂O
(B) 2 MnO₂ + HCl = 2 MnCl₂ + Cl₂ + H₂O
(C) MnO₂ + 3 HCl = MnCl₂ + 3 Cl₂ + H₂O
(D) MnO₂ + 4 HCl = MnCl₂ + Cl₂ + 2 H₂O
Answer:
(D) MnO₈ + 4 HCl = MnCl₂ + Cl₂ + 2 H₂O

Question 13.
Chemical equation provides :
(A) some informations
(B) all informations
(C) no informations
Answer:
(A) some informations

Question 14.
Ammonium cyanate changes to urea on heating is an example of :
(A) decomposition reaction
(B) rearrangement reaction
(C) direct combination reaction
Answer:
(B) rearrangement reaction

Question 15.
NaOH + HCl = NaCl + H₂ O; the type of reaction is :
(A) substitution reaction
(B) addition reaction
(C) neutralisation reaction
Answer:
(C) neutralisation reaction

Question 16.
The balanced equation for the chemical equation
FeCl₃ + SnCl₂ → FeCl₂ + SnCl₄ is :
(A) 2 FeCl₃ + SnCl₂ = 2 FeCl₂ + SnCl₄
(B) FeCl₃ + 2 SnCl₂ = FeCl₂ + 2 SnCl₄
(C) 3 FeCl₃ + SnCl₂ = 3 FeCl₂ + SnCl₄
Answer:
(A) 2 FeCl₃ + SnCl₂ = 2 FeCl + SnCl₄

Question 17.
The balanced equation for the chemical equation
Ag₂ SO₄ + BaCl₂ → BaSO₄ + AgCl is :
(A) Ag₂ SO₄ + BaCl₂ = BaSO₄ + AgCl
(B) Ag₂ SO₄ + BaCl₂ = BaSO₄ + 2 AgCl
(C) Ag₂ SO₄ + 2 BaCl₂ = 2 BaSO₄ + AgCl
Answer:
(B) Ag₂ SO₄ + BaCl₂ = BaSO₄ + 2 AgCl

Question 18.
Which of the following contains least number of molecules ?
(A) 1.12 L SO₂ at STP
(B) 1 g mole SO₂
(C) 32 g SO₂
(D) 4 × 10²³ molecules of SO₂
Answer:
(A) 1.12 LSO₂ at STP

Question 19.
No. of atoms present in 3.7 g moles of nitrogen is :
(A) 4.45 × 10²⁴
(B) 6.023 × 10²⁴
(C) 1.204 × 10²⁴
(D) 3.023 × 10²³
Answer:
(A) 4.45 × 10²⁴

Question 20.
Volume of CO₂ produced at STP from 1 mole of calcium carbonate is:
(A) 22.4 L
(B) 11.2 L
(C) 5.6 L
(D) 11 L
Answer:
(A) 22.4 L

Question 21.
Who put forward the law of conservation of mass ?
(A) Cannizarro
(B) Lavoisier
(C) Dulton
(D) Ge Lusac
Answer:
(B) Lauoisier

Question 22.
Vapour density of ozone (0 = 16) is :
(A) 16
(B) 24
(C) 32
(D) 48
Answer:
(B) 24

Question 23.
Vapour density of a gas is 8. At NTP mass of 11.2 L of this gas is:
(A) 22.4 g
(B) 16 g
(C) 8 g
(D) 11.2 g
Answer:
(C) 8 g

Question 24.
Volume of CO₂ produced at STP from 2 mole of calcium Carbonate is :
(A) 5.6 L
(B) 11.2 L
(C) 22.4 L
(D) 44.8 L
Answer:
(D) 44.8 L

Question 25.
What is the percentage composition of sulphur in sulphur dioxide?
(A) 25 %
(B) 50 %
(C) 60 %
(D) 75 %
Answer:
(B) 50 %

Question 26.
Number of molecules in 1 L of water is :
(A) \(\frac{10 \times 10^{23}}{22.4}\)
(B) \(\frac{18 \times 6.023 \times 10^{23}}{1000}\)
(C) \(\frac{6.023 \times 10^{23}}{22.4}\)
(D) 6.023 × 10²³
Answer:
(B) \(\frac{18 \times 6.023 \times 10^{23}}{1000}\)

Question 27.
Vapour density and molecular weight of a gaseous substance are related as :
(A) 2 × M = V.D
(B) \(\frac{M}{2}\) = V.D.
(C) M = \(\frac{VD}{2}\)
(D) M = V.D.
Answer:
(B) \(\frac{M}{2}\) = V.D.

Question 28.
The term which defines the mass of a given volume of a gas compared to the mass of an equal volume of hydrogen is :
(A) density
(B) mole fraction
(C) molecular weight
(D) vapour density
Answer:
(D) vapour density

Question 29.
What is the SI unit of vapour density ?
(A) Kg / m³
(B) g / cm³
(C) mole
(D) unit less
Answer:
(D) unit less

Question 30.
Mass of 112 ML O, at NTP is :
(A) 0.64 g
(B) 0.96 g
(C) 0.32 g
(D) 0.16 g
Answer:
(D) 0.16 g

Question 31.
The number of moles in 1.1 g CO₂ is
(A) 0.0025
(B) 0.025
(C) 0.25
(D) 2.5
Answer:
(B) 0.025

Fill in the blanks :

1. 49g H₂SO₄ = _______ mole.
Answer:
0.5 mol

2. Calcium carbonate contains _______ % calcium.
Answer:
40

3. Empirical formula is the formula of a compound which gives the _______ whole number ratio of the atoms of various elements present in one molecule of the compound.
Answer:
simple

4. Molecular formula is the formula of a compound which gives the _______ number of the atoms of various elements present in one molecule of the compound.
Answer:
actual

5. Molecular formula = n × _______.
Answer:
Empirical formula

6. Percentage of an element in a chemical compound is the number of parts by weight of its present in _______ parts by weight of the compound.
Answer:
100

7. Weight of oxygen obtained on heating. 24.5 g KClO₃ is _______.
Answer:
9.6 g

8. Empirical formula of a compound is HO and its molecular weight is 34. Therefore its molecular formula is _______.
Answer:
H₂ O₂

9. A chemical equation is one where the formulae of the _______ of a chemical reaction are connected with plus (+) signs in one set and those of the products are similarly connected in another set.
Answer:
reactants.

10. In double decomposition process, two different compounds, react chemically to produce two new compounds by mutual _______ of radicals.
Answer:
interchange

11. Decomposition or analysis is a process where a compound _______ into simpler substances.
Answer:
splits

12. A symbolic chemical reaction may be called a chemical equation only when it is balanced by putting least numericals as _______ before the symbols and formulae in it.
Answer:
co-efficients

13. Chemical reaction means a permanent _______ between the atoms or radicals of the combining substances.
Answer:
rearrangement

14. CO + Cl₂ = COCl₂ : This is a _______ reaction.
Answer:
addition reaction

15. In a balanced chemical equation _______ sign is placed instead of the arrow sign.
Answer:
equal

16. CuO + H₂ = Cu + H₂O; it is an _______ reaction.
Answer:
oxidation-reduction

17. There are many _______ of a chemical equation.
Answer:
limitations

18. Zn + NaOH → H₂ + _______.
Answer:
Na₂ ZnO₂

19. MnO₂ + HCI → MnCl₂ + _______ + H₂ O
Answer:
Cl₂

20. Mg + CO₂ → _______ + C
Answer:
MgO

21. KClO₃ → KCI + _______.
Answer:
O₂

22. A chemical equation does not provide information regarding the _______ of the reactants and products.
Answer:
nature

23. Fe + CuSO₄ = Cu + FeSO₄; it is a _______ reaction
Answer:
substitution

24. From a chemical equation, the time required for completion of the reaction is not _______.
Answer:
known

25. If the reactants and products are all gaseous then at the same temperature and pressure the ratio in _______ is known.
Answer:
volumes

26. 12 g carbon combines with 32 g oxygen producing _______ litre of carbondioxide at NTP.
Answer:
22.4

27. From a chemical equation, the time required for the _______ of the reaction is not known.
Answer:
completion

28. The law of conservation of mass is shown to be _______ for a chemical equation.
Answer:
valid

Well structured WBBSE Class 10 Physical Science MCQ Questions Chapter 8.5 Metallurgy can serve as a valuable review tool before exams.

Metallurgy Class 10 WBBSE MCQ Questions

Multiple choice questions (MCQ) :

Question 1.
Most of the plants contain :
(A) Iron
(B) Zinc
(C) Sodium
(D) Potassium
Answer:
(D) Potassium.

Question 2.
Malachite is mineral containing :
(A) Magnesium
(B) Aluminium
(C) Copper
(D) Tin
Answer:
(C) Copper

Question 3.
The most electropositive alkali metal is :
(A) Li
(B) Na
(C) K
(D) Cs
Answer:
(D) Cs.

Question 4.
Calcium is extracted by the electrolysis of :
(A) CaCl₂ solution
(B) CaSO₄ solution
(C) fused CaCl₂
(D) fused Ca₃(PO₄)₂
Answer:
(C) fused CaCl₂

Question 5.
Which of the following is not the ore of magnesium ?
(A) Carnallite
(B) Dolomite
(C) Gypsum
(D) Magnesite
Answer:
(C) Gypsum.

Question 6.
Magnesium is isolated by the electrolysis of :
(A) fused MgCl₂
(B) MgCl₂ solution
(C) MgSO₄ solution
(D) MgO dissolved in MgCl₂
Answer:
(A) fused MgCl₂

Question 7.
Dolomite is an ore of magnesium and it is :
(A) MgCO₃
(B) MgCO₃, CaCO₃
(C) MgCl₂, KCl, 6H₂O
(D) None of these
Answer:
(B) MgCO₃, CaCO₃

Question 8.
Carnallite is an ore of magnesium and it is :
(A) K₂SO₄, MgSO₄, MgCl₂,6H₂O
(B) MgSO₄, H₂O
(C) MgCl₂,KCl, 6H₂O
(D) None of these
Answer:
(C) MgCl₂,KCl, 6H₂O

Question 9.
Calcium oxide is also called : ……………….
(A) milk of lime
(B) quick lime
(C) lime stone
(D) slaked lime
Answer:
(B) quick lime

Question 10.
One of the important uses of quick lime is :
(A) in bleaching silk
(B) in drying gases and alcohol
(C) as a purgative
(D) in dyeing cotton
Answer:
(B) in drying gases and alcohol

Question 11.
Heating of pyrites to remove sulphur is called as:
(A) Roasting
(B) Calcination
(C) Smeting
(D) Fluxing
Answer:
(A) Roasting.

Question 12.
The element which is some times found in native state is :
(A) Al
(B) Cu
(C) Fe
(D) Mg
Answer:
(B) Cu

Question 13.
The fluorspar is :
(A) CaSO₄
(B) BaSO₄
(C) CaF₂
(D) CaCO₃
Answer:
(C) CaF₂

Question 14.
Which of the following is not the ore of calcium ?
(A) Gypsum
(B) Lime stone
(C) Dolomite
(D) Carnallite
Answer:
(D) Carnallite.

Question 15.
The chief ore of aluminium is :
(A) Feldspar
(B) Bauxite
(C) Mica
(D) Kaolin
Answer:
(B) Bawxite.

Question 16.
Baeyer’s process is used for the purification of :
(A) Boron
(B) Aluminium
(C) Titanium
(D) None of these
Answer:
(B) Aluminium

Question 17.
Alumina is :
(A) acidic
(B) basic
(C) neutral
(D) amphoteric
Answer:
(D) amphoteric

Question 18.
Pin iron is also called :
(A) Wrought iron
(B) Cast iron
(C) Steel
(D) Stainless steel
Answer:
(B) Cast iron

Question 19.
Blast furnace is used in the metallurgy of :
(A) Aluminium
(B) Gold
(C) Iron
(D) Silver
Answer:
(C) Iron

Question 20.
Haematie is :
(A) Fe₃ O₄
(B) Fe₃ O₃
(C) Fe₂ O₃ Cao
(D) None of these.
Answer:
(B) Fe₃ O₃

Question 21.
One of the following is not the ore of copper :
(A) Copper glance
(B) Azurite
(C) Malachite
(D) Corrundum
Answer:
(D) Corrundum

Question 22.
Froth floatation process is used in the metallurgy of :
(A) chloride ores
(B) sulphide ores
(C) oxide ores
(D) amalgam
Answer:
(B) sulphide ores

Question 23.
Which of the following elements is present in haemoglobin ?
(A) Mg
(B) Fe
(C) Cu
(D) Zn
Answer:
(B) Fe

Question 24.
Metal present in insulin is :
(A) Copper
(B) Iron
(C) Zinc
(D) Magnesium
Answer:
(C) Zinc.

Question 25.
In electrorefining of copper, some gold is deposited as :
(A) Anode mud
(B) Cathode mud
(C) Cathode
(D) Electrolyte
Answer:
(A) Anode mud

Question 26.
In blast furnace, the highest temperature is in :
(A) reduction zone
(B) slag formation zone
(C) fusion zone
(D) combustion zone
Answer:
(D) combustion zone

Question 27.
Which is the more pure iron ?
(A) cast iron
(B) pig iron
(C) steel
(D) wrought iron
Answer:
(D) Wrought iron

Question 28.
Which is extensively used for making aeroplane body ?
(A) Zn
(B) Cu
(C) Fe
(D) Al
Answer:
(D) Al

Question 29.
Which alloy does not contain copper ?
(A) mistch metal
(B) bell metal
(C) german silver
(D) delta metal
Answer:
(A) Mistch metal

Question 30.
Percentage of silver in german silver is :
(A) 55
(B) 0
(C) 0.5
(D) 24
Answer:
(B) 0

Question 31.
Which is not mineral ?
(A) sulphur
(B) haematite
(C) petroleum
(D) zincite
Answer:
(C) Petroleum

Question 32.
Electrolysis of molten NaCl produces Na and Cl, because :
(A) Na is oxidised B
(B) C is oxidised
(C) Both are oxidised
(D) none of these are oxidised or reduced
Answer:
(B) Cl is Oxidised

Question 33.
In thermite process which is used as reducing agent ?
(A) carbon
(B) iron
(C) aluminium
(D) zinc
Answer:
(C) aluminium

Question 34.
In cathodic protection of iron which is acting as anode?
(A) iron
(B) magnesium
(C) platinum
(D) H₂O
Answer:
(B) magnesium

Question 35.
The green patches form on the surface of copper is :
(A) CuSO₄
(B) CU(OH)₂
(C) CuO
(D) CuSO₄ . 3 Cu(OH)₂
Answer:
(D) CuSO₄ . 3 Cu(OH)₂

Question 36.
Which alloy among the following Is used In electrical fittings?
(A) German silver
(B) Brass
(C) Alnico
(D) Bell metal
Answer:
(B) Brass

Question 37.
What should be used to remove the green patties formed on the copper surface?
(A) detergent water
(B) lemon juice
(C) sand paper
(D) washing soda
Answer:
(B) lemon juice

Question 38.
Aluminium is responsible for
(A) Wilson’s disease
(B) Hepatitis-B
(C) Alzheimer’s disease
(D) Perkinson’s disease
Answer:
(C) Alzheîmer’s disease

Question 39.
The metal which can be extracted by simply heating the cinnabar ore mains: –
(A) mercury
(B) zinc
(C) copper
(D) iron
Answer:
(A) mercury

Question 40.
What are the constituents of alloy solder?
(A) Lead, Zinc
(B) Copper, tin
(C) Lead, tin
(D) Copper, Zinc
Answer:
(C) Lead, tin

Question 41.
Which metal is extracted by the electrolytic reduction of their molten chlorides or oxides?
(A) sodium
(B) iron
(C) zinc
(D) copper
Answer:
(A) sodium

Question 42.
Two metals which can be extracted by heating their suiphides in air,
(A) Na & Cu
(B) Cu & Ai
(C) K & Zn
(D) Hg & Cu
Answer:
(D) Hg & Cu

Question 43.
Which ore is used as a reducing agent in thermite process?
(A) Chromium
(B) manganese
(C) aluminium
(D) iron
Answer:
(C) aluminium

Question 44.
Food cans are coated with tin and not with zinc because
(A) Zinc has higher melting point than tin
(B) Zinc is costlier than tin
(C) Zinc is more reactive than tin
(D) Zinc is less reactive than tin
Answer:
(C) Zinc is more reactive than tin

Question 45.
Which of the following methods is suitable for preventing an iron fry- 4ng pan from rusting?
(A) Applying grease
(B) Applying paint
(C) Applying a coating of zinc
(D) All of the above
Answer:
(D) All of the above

Question 46.
Activity of the metals (in the reactivity series) decreases in the order:
(A) K > Al > Zn > Au
(B) K > AI > Au > Zn
(C) Au < K < Zn < AI
(D) K > Zn > Au >Al
Answer:
(A) K > Al > Zn > Au

Fill in the Blanks:

1. _______ disease occurs due to abnormal copper metabolism.
Answer:
wilson’s

2. When exposed to moist air for a prolonged time, _______ coloured patches are formed on copper surface.
Answer:
green

3. A shining aluminium surface gradually loses Its shine due to formation of ____
Answer:
aluminium oxide

4. Brass Is an alloy of copper and ____
Answer:
zinc

5. Constantan is an alloy of copper and ____
Answer:
nickel

6. Rusting is faster in presence of _______ ion.
Answer:
chloride

7. Galvanization is the process of applying a thin layer of _______ on ion objects.
Answer:
zinc

8. Metals of _______ activity are extracted by reduction of their oxide with carbon.
Answer:
moderate

9. Haematite is an ore of _______
Answer:
aluminium

10. Duralumin is an alloy of _______
Answer:
aluminium

State whether the following statement is True or False :

1. Aluminium is responsible for Alzheimer’s disease.
Answer:
True

2. Rust is actually hydrated iron oxide.
Answer:
True

3. Cooking utensils made up of aluminium are often anodized
Answer:
True

4. Corrosion of iron can be modeled as a short-circuited electrochemical ceil.
Answer:
True

5. Rusting requires either the presence of air or presence of water.
Answer:
False

6. Lemon juice should not be kept in a copper vessel.
Answer:
True

7. Mercury is extracted by heating its oxide.
Answer:
True

8. In reactivity series of metals, sodium is placed higher than iron.
Answer:
True

9. Stainless steel has a very low carbon content.
Answer:
True

10. Calamine is an ore of calcium.
Answer:
False

11. Bauxite is an ore of zinc.
Answer:
false

12. All the ores are minerals but not all the minerals are ores.
Answer:
True

Well structured WBBSE Class 10 Physical Science MCQ Questions Chapter 2 Behaviour of Gases can serve as a valuable review tool before exams.

Behaviour of Gases Class 10 WBBSE MCQ Questions

Multiple Choice Questions (MCQ) :

Question 1.
For liquefaction of gas, the favourable conditions are :
A. low temperature and low pressure
(B) low temperature and a catalyst
(C) low temperature and high pressure
(D) low temperature, high pressure and a catalyst.
Answer:
(B) Low temperature and high pressure

Question 2.
The critical temperature of a gas is the temperature :
(A) below which it cannot be liquefied
(B) at which it solidifies
(C) above which it cannot be liquefied
(D) above which it can no longer remain in the gaseous state.
Answer:
(D) Above which it cannot be liquefied

Question 3.
P,V,T stand for pressure, volume and temperature of a gas. Which of the following will expres Boyle’s law?
(A) V × T when P is constant
(B) V × \(\frac{1}{P}\) when T is constant
(C) PV=RT
(D) PV = n RT
Answer:
(B) V × \(\frac{1}{P}\) when T is constant

Question 4.
Gases often deviate from the ideal gas behaviour becape their molecules:
(A) posses negligible volume
(B) are polyatomic
C. have forces of attraction between them
(D) are not attracted to one another
Answer:
(C) Have forces of attraction between them

Question 5.
One of the following is not the postulate of the kinetic theory of gases :
(A) the actual volume of the molecules is negligible compared to the volume of the gas
(B) the molecules remain in ceaseless motion
C there are sufficient attractive forces between the molecules
(D) the average kinetic energy of the gas molecules is directly proportional to the absolute temperature.
Answer:
(C) There are sufficient attractive forces between the molecules.

Question 6.
Which of the following is valid at absolute zero?
(A) Kinetic energy of the gas becomes zero, but the molecular motion does not become zero
(B) Kinetic energy of the gas becomes zero and the molecular motion also becomes zero,
(C) Kinetic energy of the gas decreases but does not become zero
(D) None of the above.
Answer:
(D) None of the above

Question 7.
The pressure of real gases is less than the pressure of an ideal gas because of :
(A) increase in the number of collisions
(B) finite size of the molecules
(C) increase in kinetic energy
(D) intermolecular forces?
Answer:
(D) Intermolecular forces.

Question 8.
The temperature at which a real gas obeys the ideal gas laws over an appreciable pressure range is called the :
(A) critical temperature
(B) inversion temperature
(C) transition temperature
(D) Boyle’s temperature
Answer:
(D) Boyle’s temperature

Question 9.
Attractive forces and size effects in a gas can be neglected at:
(A) low temperature
(B) high pressure
(C) low pressures and high temperatures
(D) low temperatures and high pressures
Answer:
(C) Low pressures and high temperatures

Question 10.
An ideal gas le one which:
(A) obeys gas laws
(B) obeys Boyle’s law
(C) obeys Charle’s law
(D) Avogadro’s law.
Answer:
(A) obeys gas laws

Question 11.
The volume of any gas at this temperature becomes zero :
(A) +273° C
(B) -273° C
(C) 273 K
(D) -273 K
Answer:
(B) -273° C

Question 12.
Pressure cooker reduces cooking time because :
(A) the heat is more easily distributed
(B) the higher pressure tenderizes the food
(C) the boiling point of water inside is elevated
(D) a large flame is used
Answer:
(C) the boiling point of water inside is elevated

Question 13.
In the ideal gas equation PV = nRT, the value of R depends upon:
(A) unit of measurement
(B) temperature of gas
(C) pressure of gas
(D) nature of gas
Answer:
(A) unit of measurement

Question 14.
At constant mass and constant volume, the relation between pressure and temperature is :
(A) Boyle’s law
(B) Charle’s law
(C) Gay Lussac’s law
(D) None of these.
Answer:
(C) Gay Lussac’s law

Question 15.
At constant mass and constant temperature the relation between volume and pressure is :
(A) Charle’s law
(B) Boyle’s law
(C) Gay Lussac’s law
(D) None of these.
Answer:
(B) Boyle s law

Question 16.
The value of absolute temperature in celsius scale is :
(A) 0° C
(B) -100° C
(C) -273° C
(D) -373° C
Answer:
(C) -273° C

Question 17.
The boiling point of water in Kelvin scale is :
(A) 0 K
(B) 373 K
(C) 100 K
(D) 273 K
Answer:
(B) 373 K

Question 18.
What will be the value of 127° C in Kelvin scale?
(A) 127 K
(B) 400 K
(C) 146 K
(D) 200 K
Answer:
(B) 400 K

Question 19.
The relation between 100° C and 373 K is
(A) 100° C > 373 K
(B) 100° C < 373 K
(C) 100° C = 373 K
(D) Non of these.
Answer:
(C) 100° C = 373 K

Question 20.
At NTP, if the volume of any gas is 10 lit then at 27° C and 750 mm pressure what will be its volume :
(A) 11.1 lit
(B) 15 lit
(C) 8.1 lit
(D) 8.2 lit
Answer:
(A) 11.1 lit

Question 21.
A gas having temperature 0° C is heated so that its pressure and volume are doubled. What will be the final temperature of the gas?
(A) 1092 K
(B) 1002 K
(C) 999 K
(D) 980 K
Answer:
(A) 1092 K

Question 22.
The relation between celsius and absolute scale is :
(A) T = t + 273
(B) T = t – 273
(C) t = T + 273
(D) t = T – 273
Answer:
(A) T = t + 273

Question 23.
Normal pressure is :
(A) 1.013 × 10⁶ dyne / cm²
(B) 2.013 × 10⁶ dyne / cm²
(C) 1.05 × 10⁶ dyne / cm²
(D) 1.09 × 10⁶ dyne / cm²
Answer:
(A) 1.013 × 10⁶ dyne cm²

Question 24.
P₁ V₁ = P₂ V₂ is related to :
(A) Boyle’s law
(B) Charle’s law
(C) Regnault’s law
(D) None of these
Answer:
(A) Boyle s law

Question 25.
The relation between pressure, temperature and density of a gas is:
(A) \(\frac{P}{DT}\) = constant
(B) \(\frac{P}{DT}\) = constant
(C) \(\frac{PD}{T}\) = constant
(D) None of these
Answer:
(B) \(\frac{P}{DT}\) = constant

Question 26.
Volume of 4.4 g of CO₂ at STP is :
(A) 22.4 L
(B) 2.24 L
(C) 224 L
(D) 44.8 L
Answer:
(A) 2.24 L

Question 27.
Gas deviates from ideal gas nature because molecules.
(A) are colourless
(B) attract each other
(C) contain covalent bond
(D) show Brownian movement
Answer:
(B) attract each other

Question 28.
A gas will approach ideal behaviour at :
(A) low temperature and low pressure
(B) low temperature and high pressure
(C) high temperature and low pressure
(D) high temperature and high pressure.
Answer:
(C) high temperature and low pressure

Question 29.
Kinetic theory of gases proves :
(A) only Boyle’s law
(B) only Charle’s law
(C) only Avogadro’s law
(D) all of these
Answer:
(D) all of these

Question 30.
The unit of p v in the equation Pv = nRT is
(A) N / m
(B) N.m
(C) N / m²
(D) N-m²
Answer:
(B) N.m

Question 31.
Which of the following order is corect?
(A) 0 K > 0° F > 0° C
(B) 0 K < 0° F < 0° C (C) 0°C > 0° F > 0 K
(D) 0 K = 0° F = 0° C
Answer:
(B) 0 K < 0° F < 0° C

Question 32.
All the temperature are positive when expressed in
(A) Celsius scale
(B) Fahreuheit scale
(C) Kelvin scale
(D) None of these
Answer:
(C) Kelvin scale

Question 33.
Real gas behaviour differs from ideal gas behaviour because the molecules of real gases
(A) attract one another
(B) collide
(C) have mass
(D) are arranged in a regular geometric pattern
Answer:
(A) attract one another

Question 34.
Collisions of Helium atoms with the walls of a closed container cause :
(A) condensation
(B) decrease in volume
(C) gas pressure
(D) an overall loss of energy
Answer:
(C) gas pressure

Question 35.
Which is the correct relationship between centigrade and Kelvin scale?
(A) T = t + 273
(B) \(\frac{T}{5}\) = \(\frac{t-32}{9}\)
(C) T = t – 273
(D) t = T + 273
Answer:
(A) T = t + 273

Question 36.
If the pressure of any gas be increased keeping its temperature and mass constant, then its density will :
(A) increase
(B) decrease
(C) remain same
(D) depend upon other factors
Answer:
(A) increase

Question 37.
A real gas behaves as an ideal gas :
(A) at very low pressure and very low temperature
B) at very low pressure and very high temperature
(C) at very high pressure and very low temperature
(D) at very high pressure and very high temperature
Answer:
(B) at very low pressure and very high temperature

Question 38.
Volume-temperature relationship was given by
(A) Boyle
(B) Charles
(C) Avogadro
(D) Gay Lussac
Answer:
(B) Charles

Question 39.
At a fixed temperature and pressure, the average distance between molecules would be greatest in a sample of :
(A) air
(B) water
(C) wood
(D) diamond
Answer:
(A) air

Question 40.
Unit of molar mass of a gas is :
(A) gram
(B) gram / cm³
(C) g / mol
(D) mol
Answer:
(C) g / mol

Question 41.
Which of the following plots is not linear for an ideal gas ?
(A) P-T
(B) V-T
(C) P-V
(D) P-d
Answer:
(C) P-V

Fill in the blanks :

1. According to kinetic theory of gases, a gas consists of discrete particles called ________.
Answer:
molecules

2. The scale of temperature with -273°C as zero is called ________.
Answer:
Absolute or Kelvin temperature scale

3. Real gases do not behave like ideal gases because they have inter molecular ________ and the molecules do not have negligible volume.
Answer:
attraction

4. The law which describes the relationship between the volume and temperature of a gas at constant pressure is called ________.
Answer:
Charle’s law

5. According to the kinetic theory of gases, the kinetic energy of gases is directly proportional to its ________.
Answer:
absolute or Kelvin temperature

6. The volume of a gas is zero at ________ temperature.
Answer:
absolute

7. At constant temperature for a given volume of gas the product of its pressure and its volume is ________.
Answer:
constant

8. The value of absolute zero is ________ on Celsius scale.
Answer:
-273°C

9. The equation of ideal gas for n gram-moles is ________.
Answer:
P V=n R T

10. The volume of a given mass of gas varies directly as ________ temperature at constant pressure.
Answer:
absolute

11. Gases like H₂, O₂, N₂, Cl₂ etc. which obey Boyle’s law and Charle’s law at low pressure and ________ temperature are called real gases.
Answer:
high

12. The constant quantities in Boyle’s law are ________ and temperature.
Answer:
mass

13. Gaseous molecules have no mutual force of ________, so they are always in an incessant motion.
Answer:
atrraction

14. If heat is supplied to a gas, its molecules move with more ________, so temperature of the gas rises.
Answer:
energy

15. The normal temperature is taken as 0°C or ________ K and the normal pressure is taken as 76 cm mercury or 1 atmosphere.
Answer:
273

16. At constant temperature, the volume of a given mass of gas varies ________ as its pressure.
Answer:
inversely

17. For a given mass of a gas or vapour at a constant temperature, pressure × _______ = constant.
Answer:
volume

18. The boiling point of water is ________ Kelvin.
Answer:
273

19. At ________ °C, the gas molecules become motionless.
Answer:
(-) 273

20. 330 K = _______ ° C
Answer:
57

21. The pressure of a gas is determined by ________.
Answer:
Manometer

22. The value of normal pressure in SI system is ________ pascal.
Answer:
1.013 × 10⁵

23. Absolute scale reading = Celsius scale reading + ________.
Answer:
273

24. Law of pressure is known as ________.
Answer:
Regnault’s law

25. Any real gas becomes ________ before it reaches to absolute zero.
Answer:
liquefied

26. Equal volumes of two gases under similar conditions of temperature contain ________ number of molecules.
Answer:
same

27. The volume of gas is zero at ________ temperature.
Answer:
absolute

28. At constant temperature for a given volume of gas the product of its pressure and its volume is ________.
Answer:
constant.

29. The velocities of molecules ________ with rise of temperature.
Answer:
increase.

30. The equation of ideal gas for n gram-moles is ________.
Answer:
PV = nRT

31. Zero reading of the kelvin scale is known as ________ zero.
Answer:
absolute

32. The temperature above which a gas behaves like and ideal gas is called ________ temperature.
Answer:
Boyles

33. Value of R in Ltt-atm mol^-1 k^-1 unit is ________.
Answer:
0.082

34. The number of molecules present in a gram molecule mass of a substance is called ________.
Answer:
Avogadro’s number

35. Molar volume of an ideal gas is ________ ML at N.T.P.
Answer:
22400

36. Density of moist air is ________ than that of dry air.
Answer:
less

37. At a fixed temperature, if the pressure of the gas is doubled, volume of the gas is ________.
Answer:
halved

38. PV versus P curve of an ideal gas gives a straight line parallel to ________ axis.
Answer:
X

39. Under similar condition of temperature and pressure, equal volumes of all gases contain same number of ________.
Answer:
molecules

40. R is called gas ________ constant.
Answer:
universal

State whether the following statement is True or False : VSA

1. Freezing polnt of water in absolute scale is 290 K.
Answer:
False

2. Gases show deviations from ideal behaviour at high temperatures and high pressures.
Answer:
False

3. The value of Avogadro Number is 6.022 × 10²³
Answer:
True

4. Unit of R in litre atmosphere per kelvin per mole.
Answer:
True

5. The N.T.P is 25° c and 1 atm. pressure.
Answer:
False

6. P versus 1 / v curve gives a straight line.
Answer:
True

7. The lowest temperature of this universe is O K.
Answer:
True

8. The slope of V versus T curve at higher pressure is steeper.
Answer:
False

9. According to kinetic theory of gases, intermolecular attractive force exists between gas molecules.
Answer:
False

10. Volume of a gas is actually the volume of the container in which the gas is kept.
Answer:
True

11. At Constant pressure, as the temperature increases, the volume of the gas also increases.
Answer:
True

12. The rate of diffusion of methane is more than that of Sulphur dioxide.
Answer:
True

13. Pressure is also expressed in ‘mm of Hg’ unit.
Answer:
True

14. The inter molecular force of attriction is least in gas.
Answer:
True

15. The collision of gas molecules with the walls of the container is manifested as pressure.
Answer:
True

Comprehensive WBBSE Class 10 Physical Science Notes Chapter 1 Concerns About Our Environment can help students make connections between concepts.

Concerns About Our Environment Class 10 WBBSE Notes

Environment : It is defined as the sum total of physical and biological factors that directly influence the survival, growth, development and reproduction of organisms.

Environmental chemistry: The branch of chemistry which deals with the study of various chemical phenomena occuring in the environment is called, environmental chemistry.

Environmental components of earth : Earth’s environment is composed of the following components :
1. Atmosphere 2. Hydrosphere 3. Lithosphere 4. Biosphere Among these the first three components are abiotic while the fourth one is biotic.

1. Atmosphere: This comprises a blanket of gaseous layer that extends to a height of about 1600 km above the surface of earth.
The atmosphere has been divided into four distinct zones. These are :

• Troposphere
• Stratosphere
• Mesosphere
• Thermosphere.

Different regions of atmosphere

2. Hydrosphere: It includes all sources of water such as seas, oceans, lakes, rivers, fountains, polar regions, glaciers, ground water etc.

3. Lithosphere: It comparises of the solid crust of the earth, made up of rocks forming the outermineral cover. It includes soil, minerals, organic matters etc. and extends up to a depth of about 30 km from the earth’s surface.

4. Blosphere 3 It is that portion of the earth where living organisms exist and interact with one another and also with the non-living components.
Biosphere consists of all the three regions, e.g. soil, water, air etc. where living beings exist.

Temperature distribution with height above earth’s surfaces :

Ozone layer: In the lower region of the stratosphere (the region at the hieght of 15 km to 35 km from the ground) there exists a layer of ozone gas. This layer is called ozone layer or ozonosphere. Almost 90 % of total ozone gas exists in this layer.

Formation of ozone layer : O₂(Oxygen molecule) present in the stratosphere absorbs UV (ultra violet) (λ = 255 nm ) radiation coming from the sum and decomposes to form oxygen atom (O). This atomic oxygen combines with oxygen molecule to form ozone molecule.

Formation of O₂ from O₃ ; Ozone molecules also absorbs UV-radiation and gets converted into oxygen molecule (O₂)

Fixation of quantity of ozone in the stratosphere: In the ozone layer of the stratosphere, these two opposite process (i.e. formation of ozone molecule and the decomposition of ozone molecule) occur in a cyclic order and finally attains a state of equilibrium. Because of the existense of such an equilibrium state, quantify of ozone in the stratosphere remains fixed.

Role of ozone layer in the environment : Ozone layer absorbs most of the harmful UV-radiation emitted by the sun because this ray is utlised in the production and decomposition of ozone.

Harmful effect of UV-radiation:

1. ultraviolet radiation causes cancer in human skin.
2. damages the cornea of the eyes and develops premature cataract.
3. In addition, immunity against diseases and fertility in living beings decreases.

Ozone hole (Depletion of Ozone layer); The phenomenon of thinning of the Ozone layer of the stratosphere is known as depletion of ozone layer or ozone hole.
In 1982, the British scientist Jo Foreman first observed ozone hole.

Causes of depletion of ozone layer or formation of ozone hole:; Due to the influx of several foreign substances into the atmosphere, the rate of decomposition of ozone has far exceeded than that of its formation. This has resulted in the thinning of ozone layer in the stratosphere almost everywhere.

The factors which accelerate the ozone depletion are as follows :

Some chemical substances belonging to the class of chlorofluorocarbons (Freons or CFC ) are mainly responsible for the formation of ozone hole.

Name	Formula	Trade Name
Trichloro fluoro methane	CFCl3	Freon-1
Dichloro difluoro methane	CF2Cl2	Freon-12
Dichloro fluoro methane	CHCl2F	Freon-22
Dichloro trifluoro ethane	CHCl2-CF3	Freon-113
Dichloro fluoro ethane	CH3-CCl2F	Freon-1146

Use of the above mentioned chemicals :

• refrigerants
• propellants in aerosols
• foaming agent in plastic production
• as solvents for various purposes.

A cyclic process continues, which eventually causes depletion of ozone layer.

It has been experimentally found that a single Cl atom is capable of decomposing millions of O₃ molecules.

Halocarbons : It has been found experimentally that halons i.e. halocarbons which are generally used as fire extinguishers and as pesticides e.g. Halon-1301 i.e. bromo trifluoro methane (CF₃ Br), Halon-1211 i.e. bromochloro difluoro methane (CF₂BrCl). Halons are stable in the troposphere. But in the stratosphere, they absorb UV-radiation and decompose to produce active bromine atoms ( Bi). Thus produced active Br atoms convert ozone molecule of ozone layer to oxygen molecule and free radical bromine monoxide ( BrO ). They produced bromine monoxide (BrO) reacts with more ozone to give more oxygen and active Br atoms. In this way, the entire process proceeds continuously in a cyclic manner which lead to decay of the ozone layer.

Oxides of Nitrogen (NO, NO₂) : The gaseous oxide of nitrogen is produced due to human activity or naturally in the troposphere. Major portion of this gas is produced in the exhaust gases of supersonic planes flying in the stratosphere and thus the gas is added directly into the stratosphere.

Here NO (Nitric oxide) gas comes in contact with the ozone and reacts to form NO₂and O₂. The NO thus reacts with Oxygen atoms and formed NO₂due to the decomposition of ozone molecules by the UV-rays. Nitrogen dioxide (NO₂) reacts with Oxygen atoms to produce back Nitric Oxide (NO) gas. This explains why the ozone molecules undergo continuous decomposition although the quantity of Nitric oxide (NO) is not diminised.

Green house: Green house is a large chamber made of glass on the soil. When the plants of tropical countries are taken to cold countries, they cannot adapt themselves to the climatic conditions of the cold countries.

Green house gases: These are some gases which are present in earth’s atmosphere e.g. carbon dioxide (CO₂), methane (CH_4), water vapour (H₂O), chlorofluoro Carbon (CFC), ozone (O₃), nitrous oxide (N₂O).

The green house gases form a layer surrounding the earth’s surface which act like that of the glass walls and roof of the green house and keep the atmosphere of earth’s surface warmer. These gases are known as green house gases.

Green house effect: The natural process by which a layer of green house gases present in the atomsphere surrounding the earth’s surface, instead of allowing the infrared radiation reflected by earth’s surface to pass out into the outer space, partly absorbs the radiated heat and reflects back the rest to the earth’s surface and thus keeps the surface of the earth and the adjacent atmosphere warm, which is suitable for the existence of the living beings, is known as green house effect.

Global warming : It has been observed that in the last few centuries the average temperature of the earth is gradually increasing. For example, during the period from 1800-1900 AD, the average increase of the earth’s temperature was found to be 0.4° C and during the period 1900-2000 AD this increase in temperature is 1° C. So it cannot be denied that the natural environment is gradually becoming warmer.

The phenomenon of gradual increase of temper all over the world is called global warming.

Causes for the increasing concentration of green house gases in the atmosphere :

1. Huge amount of coal is burnt daily in the thermal power stations for the generation of electricity.
2. Excessive use of nitrogenous fertilizers in agriculture is the cause of increasing amount of nitrous oxide and oxides of nitrogen in the atmosphere.
3. Combustion of huge amount of petrol and diesel in the automobiles and forest fires are the causes for the increase of carbon dioxide in the atmosphere.
4. Extensive use of coal, wood, LPG etc., as fuels for the cooking purpose and to meet the other needs of the growing population. In consequence of which high amount of carbon dioxide gas is being added to the atmosphere.
5. Due to the increase of paddy field, marshy lands, waste organic matters, the amount of methane gas in the atmosphere is going on increasing.

Some preventive meacures to reduce emiseion of green hotuse gases;

1. In order to decrease the amount of carbon dioxide in the atmosphere the use of fossil fuels e.g. wood, coal, petrol, diesel, kerosene, L.P.G. etc., should be reduced as far as possible.
2. Afforestation must be encouraged so that more carbon dioxide are absorbed by plants.
3. Use of chlorofluoro carbon (CFC) must be stopped totally.
4. Deforestation must be totally stopped legally.
5. Instead of using coal, electric energy can be produced by using solar energy, tidal energy, wind energy. Electricity may be produced by using nuclear energy and hydroelectricity.

The calorific value of a fuel : It is the quantity of heat produced by its combustion at constant pressure under hormal’ (standard) conditions (i.e. to 0°C and under a pressure of 76 cm Hg pressure).

Higher calorific values for some common fuels: Coke, oil, wood, hydrogen etc.

Necessity of conservation of fossile fuels :

Advantages of Fossils fuels

Easily available : Since these fossil fuels have been of such a great source of energy, more and more extractions are going on every day.

Produce large amount of Energy : Fossil fuels are easily combustible.

High Caloricfic value : All energy produced has some calorific value. The more the value, the more effective it is.

Stability : The fossil fuels are composed of the molecules of carbon and hydrogen. This makes them very stable.

Transportation : This industries need regular supply of fossil fuel like oil, gas and coal. The biggest advantage of using fossil fuels is that they can be easily stored and transported from one place to another.

Abundantly available : Though every effort is made to make the usage of alternative fuels popular, still fossil fuels are most common ones in use. This is because, these are very easily available.

Low cost : Fossil fuels are available all over the world and the methods to extract energy from them are also not that expensive.

Easy set up : Since they are widely available, the construction of fossil fuel power plant can take any where in the world as long as they get large quantities of fossil fuels to feed them.

Sources of energy :

Solar energy: Solar power harvests the energy of the sun through using collector panels to create conditions that can be turned into a kind of power. Large solar panel fields are often used in desert to gather enough power to charge small substations, and many homes use solar systems to provide for hot water, cooling and supplement their electricity.

Wind energy: Wind power is becoming more and more common. The new innovations that are allowing wind forms to appear are making them a more comman sight. By using large turbines to take available wind as the power to turn, the turbine can then turn a generator to produce electricity.

Geothermal Energy: It is the energy that is produced from beneath the earth. It is clean sustainable and environment friendly. High temperature are produced continuously inside the earth’s crust by the slow delay of radioactive particles. Hot rocks present below the earth heats up the water that produces steam. The steam is then captured that helps to move turbines. The rotating turbines then power the generators.

The biggest disavantage with geothermal energy is that it can only be produced at selected sites throughout the world. The largest group of geothermal power plants in the world is located at the Geysers, a geothermal field in california, united states.

Hydroyen Energy : Hydrogen is available with water (H₂O) and is most common element available on earth. Water contains two-thirds of hydrogen and can be found in combination with other elements. Once it is separated, it can be used as a fuel for generating electricity.

Hydrogen is a tremendous source of energy and can be used as a source of fuel of power ships, vehicles, homes, industries and rockets. It is completely renewable, can be produced on demand and does not leave any toxic emissions in the atmosphere.

Tidal Energy : Tital energy uses rise and fall of tides to convert kinetic energy of incoming and outgoing tides into electric energy. The generation of energy through tidal power is mostly prevalent in coastal areas. Huge investment and limited availability of sites are few of the draw-backs of tidal energy. When there is increased height of water levels in the ocean, tides are produced which rush back and forth in the ocean. Tidal energy is one of the renewable source of energy and produce large energy even when the tides are at low speed.

Wave Energy : Wave energy is produced from the waves that are produced in the oceans. Wave energy is renewable, environment-friendly and causes no harm to atmosphere. It can be hardnessed along coastal regions of many countries and can help a country to reduce its dependance on foreign countries for fuel. Producing wave energy can damage marine ecosystem and can also be a source of disturbance to private and commercial vessels. It is highly dependent on wavelength and can also be source of visual and noise pollution.

Hydroelectric Energy: Many people are not aware about that most of the cities and towns in the world rely on hydropower. Every time you see a major dam, it is providing hydropower to an electrical station somewhere. The power of water is used to turn generatots to produce the electricity that is then used. The problems faced with hydropower right now have to do with against of the dams.

Biomass Energy: It is produced from organic material and is commonly used throughout the world chlorophyll present in plants captures the Sun’s energy by converting carbon dioxide from the air and water from the ground into carbohydrates through the process of photosynthesis. When the plants are burned, the water and carbon dioxide is again released back into the atmosphere. Biomass generally include crops, plants, trees, yard clippings, wood chips and animal wastes. Biomass energy is used for heating and cooking in homes and a fuel in industrial production. This type of energy produces large amount of CO₂into the atmosphere.

Nuclear Power: While nuclear power remains a great subject of debate as to how safe it is to use and whether or not it is really energy efficient when you take into account the waste it produces – the fact is it remains one of the major renewable source of energy available to the world. The energy is created through specific nuclear reaction, which is then collected and used to power generators. While almost every country has nuclear generators, there are moratorium on their use or construction as scientists try to resolve safely and disposal issues for waste.

Fossil Fuels (Coal, Oil and Natural Gas): When most people talk about the different sources of energy they list natural gas, coal and oil as the options – these are all considered to be just one source of energy from fossil fuels.

Well structured WBBSE Class 10 Physical Science MCQ Questions Chapter 5 Light can serve as a valuable review tool before exams.

Light Class 10 WBBSE MCQ Questions

Multiple Choice Questions (MCQ) :

Question 1
The formation of spectrum is due to:
(A) reflection
(B) refraction
(C) dispersion of light
Answer:
(C) dispersion

Question 2.
The terminal colours of pure spectrum of white light are:
(A) Blue and violet
(B) Red and orange
(C) Red and violet
Answer:
(C) Red and violet

Question 3.
Yellow colour is called:
(A) primary
(B) secondary
(C) middle colour.
Answer:
(B) secondary colour

Question 4.
The (A) seven (B) six (C) eight colours can be seen distinctly in pure spectrum.
Answer:
(A) seven

Question 5.
The dispersion of white light was first observed by :
(A) Sir Issac Newton
(B) Boyle
(C) Max well
Answer:
(A) Sir Issac Newton

Question 6.
The would be towards the base of the prism.
(A) violet
(B) green
(C) orange
Answer:
(A) violet

Question 7.
The arrangement of seven colours of spectrum is:
(A) VIBGYOR
(B) VBIGOYR
(C) RAINBOW
Answer:
(A) VIBGYOR

Question 8.
Linear magnification is equal to:
A (length of image) / (length of the object)
(B) (length of image) × (length of the object)
C) (length of image) + (length of the object)
(D) (length of image) – (length of the object)
Answer:
(B) (length of image) × (length of the object)

Question 9.
The object is placed in between ‘f’ and ‘2f’ in convex lens, the size of image will be
(A) greater in size the object
(B) smaller in size than the object
(C) equal in size of the object.
Answer:
(A) greater in size than the object.

Question 10.
To form virtual image on the same side of the object in case of convex lens, object should be placed:
(A) in between the lens and the focus
(B) in between ‘f’ and ‘2f’
C) at ‘2f’ from the lens
(D) at a distance greater than ‘2f’ from the lens.
Answer:
(A) in beiveen the lens and the focus

Question 11.
To form the image of real, inverted and equal to the size of the object, the object should be placed:
(A) in between the lens and the focus
(B) at a distnace greater then ‘2f’ from the lens
(C) at ‘2f’ from the lens
(D) in between ‘f’ and ‘2f’
Answer:
(C) at ‘2f’ from the lens

Question 12.
A plane mirror produces a magnification of :
(A) -1
(B) +1
(C) Zero
(D) between O and + α
Answer:
(B) +1

Question 13.
When a mirror is rotated through an angle θ, the reflected ray from it turns through an angle of
(A) θ
(B) \(\frac{\theta}{2}\)
(C) 2 θ
(D) 0
Answer:
(C) 2 θ

Question 14.
An object is placed at a distance of 40 cm in front of a concave mirror of focal length 20 cm. The image produced is
(A) virtual and inverted
(B) real and erect
C) real, inverted and diminished
(D) real, inverted and of some size as the object.
Answer:
(D) real, inverted and of same size as the object.

Question 15.
A plane mirror is approaching a person at a speed of 5 cm s^-1. At what speed will his image approach him ?
(A) 10 cm s^-1
(B) 5 cm s^-1
(C) 20 cms^-1
(D) 15 cm s^-1
Answer:
(A) 10 cms^-1

Question 16.
An object is placed between two plane mirrors inclined at an angle of 30°, then total number of images formed is
(A) 12
(B) 2
(C) 11
(D) infinite
Answer:
(C) 11

Question 17.
A ray is incident at an angle 38° with a mirror. The angle between normal and reflected ray is
(A) 38°
(B) 52°
(C) 90°
(D) 76°
Answer:
(B) 52°

Question 18.
A concave mirror gives an image three times as large as the object placed at a distance of 420 cm from it. For the image to be real, the focal length should be
(A) 10 cm
(B) 15 cm
(C) 20 cm
(D) 30 cm
Answer:
(B) 15 cm

Question 19.
A concave mirror of focal length f (in air) is immersed in water (μ=\(\frac{4}{3}\)). The focal length of the mirror in water will be
(A) f
(B) [altex]\frac{4}{3}[/latrex] f
(C) \(\frac{3{4}\) f
(D) \([\frac{7{3}\) f
Answer:
(A) f

Question 20.
A mirror produces magnified erect image of an object. The nature of mirror is
(A) convex
(B) concave
(C) neither convex nor concave
(D) plane
Answer:
(B) concave

Question 21.
A ray of light is incident normally on a plane mirror. The angle of reflection will be
(A) 135°
(B) 90°
(C) 45°
(D) 0°
Answer:
(D) 0°

Question 22.
The focal length f of a spherical mirror of radius of curvature R is
(A) \(\frac{R}{2}\)
(B) R
(C) \(\frac{3}{2}\) R
(D) 2 R
Answer:
(A) \(\frac{R}{2}\)

Question 23.
In which of the following cases, man will not see image greater than himself ?
(A) Concave mirror
(B) Convex mirror
(C) Plane and Concave
(D) None of these.
Answer:
(B) Convex mirror

Question 24.
If an object is 30 cm away from a cancave mirror of focal length 15 cm, the image will be
(A) erect
(B) virtual
(C) diminished
(D) of same size
Ans:
(D) of same size

Question 25.
The number of images observable between two parallel plane mirrors is
(A) 2
(B) 4
(C) 11
(D) infinite
Ans:
(D) infinite

Question 26.
The focal length of a canvex lens is 30 cm and the size of image is a quarter of the object, then the object distance is
(A) 90 cm
(B) 60 cm
(C) 30 cm
(D) 40 cm
Ans:
(A) 90 cm

Question 27.
Focal length of a convex lens will be maximum for
(A) blue light
(B) yellow light
(C) green light
(D) red light.
Answer:
(D) red light

Question 28.
A lens is behaving as convex lens in air and concave in water then its refractive index is
(A) smaller than air
(B) greater than both air and water
(C) greater than air, but less than water
(D) almost equal to water.
Answer:
(C) greater than air, but less than water

Question 29.
The plane surface of a plano-convex lens of focal length f is silvered. It will behave as
(A) plane mirror
(B) convex mirror of focal length 2f
(C) concave mirror of focal length f/2
(D) None of the above
Answer:
(C) concave mirror of focal length f2

Question 30.
Mirage is a phenomenon due to
(A) reflection of light
(B) refraction of light
(C) total internal reflection of light
(D) diffraction of light.
Answer:
(C) total internal reflection of light.

Question 31.
The principle behind optical fibres is
(A) total internal reflection
(B) total external reflection
(C) both (A) and (B)
(D) diffraction.
Answer:
(A) total internal reflection.

Question 32.
A convex lens is dipped in a liquid whose refractive index is equal to the refractive index of the lens. Then its focal length will
(A) become zero
(B) become infinite
(C) reduce
(D) increase
Answer:
(B) become infinite

Question 33.
A convex lens will become less convergent in
(A) oil
(B) water
(C) both
(D) none
Answer:
(B) water

Question 34.
Which of the following colours suffers maximum deviation in a prism?
(A) yellow
(B) blue
(C) green
(D) orange
Answer:
(B) blue

Question 35.
The splitting of white light into several colours on passing through a glass prism is due to
(A) refraction
(B) reflection
(C) interference
(D) diffraction
Answer:
(A) refraction

Question 36.
Rainbow is formed due to a combination of
(A) refraction and absorption
(B) dispersion and focussing
(C) refraction and scattering
(D) dispersion and total internal reflection
Answer:
(D) dispersion and tota’ internal reflection

Question 37.
Which of the prism is used to see infrared spectrum of light ?
(A) rock salt
(B) nicol
(C) flint
(D) crown
Answer:
(A) rock salt

Question 38.
Myopia is due to
(A) older age
(B) shortening of eye ball
(C) irregular change in focal length
(D) elongation of eye ball.
Answer:
(D) elongation of eve ball

Question 39.
A person cannot see objects clearly beyond 2 m. The power of lens required to correct his vision will be
(A) +2 D
(B) -1 D
(C) +1 D
(D) -0.5 D
Answer:
(D) -0.5 D

Question 40.
A person uses spectacle of power +2D. He is suffering from
(A) short sightedness of myopia
(B) long sightedness of hypermetropia
(C) presbyopia
(D) astigmatism
Answer:
(B) long sighteciness of hypermetropia

Question 41.
Which of the following materials cannot be used to make a lens ?
(A) water
(B) glass
(C) clay
(D) plastic
Answer:
(C) clay

Question 42.
No matter how far you stand from a mirror, your image appears erect. The mirror is likely to be :
(A) plane only
(B) concave only
(C) convex only
(D) eighter plane or convex
Answer:
(D) eighter plane or convex

Question 43.
A ray of light suffers refraction through an equilateral prism. The deviation produced by the prism does not depend on the :
(A) angle of incidence
(B) colour of light
(C) size of the prism
(D) material of the prism
Answer:
(C) stze of the prism

Question 44.
A ray of light incident on a lens parrallel to its principal axis, after refraction passes through or appears to come from :
(A) its second focus
(B) its first focus
(C) its optical centre
(D) the centre of curvature of its second surface
Answer:
(A) its second fucus

Question 45.
The source of ultra-violet light is :
(A) electric bulb
(B) carbon arc lamp
(C) red hot iron bulb
(D) sodium vapour lamp
Answer:
(B) carbon arc lamp.

Question 46.
A mirror having a very wide fleld of view must be
(A) concave
(B) convex
(C) plane
(D) none of these
Answer:
(B) convex

Question 47.
Linear magnification (m) of a convex mirror is :
(A) greater than one
(B) less than one
(C) zero
(D) equal to one
Answer:
(B) less than one

Question 48.
Back side of a shining stainless steel spoon resembles :
(A) a concave mirror
(B) a convex mirror
(C) a plane mirror
(D) a prism
Answer:
(B) a convex mirror

Question 49.
Front side of a shining stainless steel spoon resembles
(A) a concave mirror
(B) a convex mirror
(C) a plane mirror
(D) a prism
Answer:
(A) concave mirror

Question 50.
If a concave mirror having focal length f is immersed in water (\mu=\frac{4{3), then the new focal length would be :
(A) \(\frac{4}{3}\) f
(B) \(\frac{3}{4}\) f
(C) f
(D) \(\frac{7}{4}\) f
Answer:
(C) f

Question 51.
Snell’s law is not valid when the angle of incidence is :
(A) 0°
(B) 45°
(C) 60°
(D) 90°
Answer:
(A) 0°

Question 52.
Refraction is caused by :
(A) different wave speeds
(B) more than one reflection
(C) displaced images
(D) bending
Answer:
(A) different wave speeds

Question 53.
A swimming pool appears to be 2 m deep. It’s actual depth is (\mu for water = 1.33)
(A) 2.66 m
(B) 2 m
(C) 2.34 m
(D) 2.54 m
Answer:
(A) 2.66 m

Question 54.
Which one of the following can not be used to make a lens?
(A) water
(B) transparent plastic
(C) glass
(D) iron
Answer:
(D) iron

Question 55.
The power of comblnation of two lenses of power +1.5D and -2.5 D is :
(A) -D
(B) 4 D
(C) +4 D
(D) +D
Answer:
(A) -D

Question 56.
The size of the pupil is adjusted by :
(A) cornea
(B) iris
(C) retina
(D) aqueous human
Answer:
(B) iris

Question 57.
The power of a lens is -1.5 D. It’s focal length is :
(A) -1.5 cm
(B) -15 cm
(C) 66.6 cm
(D) -66.6 cm
Answer:
(D) -66.6 cm

Question 58.
The colour of light which suffers maximum bending while passing through a glass prism is :
(A) green
(B) red
(C) yellow
(D) violet
Answer:
(D) violet

Question 59.
The three primary colours are :
(A) red, blue, yellow
(B) red, green, yellow
(C) yellow, green, orange
(D) red, green, blue
Answer:
(D) red, green, blue

Question 60.
The colour of an object is the same as the light that is:
(A) transmitted
(B) absorbed
(C) reflected
(D) All of these
Answer:
(C) reflected

Question 61.
Compared to ultraviolet waves, the wave length of infrared waves is:
(A) shorter
(B) longer
(C) the same
(D) faster
Answer:
(B) longer

Question 62.
If there were no atmosphere, the cloudless sky would have appeared
(A) blue
(B) violet
(C) red
(D) black
Answer:
(d) black

Fill in the blanks :

1. A convex lens is called a _______ lens.
Answer:
converging

2. The middle colour is _______.
Answer:
yellow

3. Yellow and blue colours are _______ colours of each other.
Answer:
complementary

4. Maggenta colour is made by mixing red and ______ colour.
Answer:
blue

5. Red flower appears ______ in green light.
Answer:
black

6. During dispersion of light, which light is splitting up into ______ colours.
Answer:
seven

7. A __________ lens is used as a magnifying glass.
Answer:
convex

8. A beam of rays of light parallel to the principal axis of a convex lens, will passes through the ______ focus after refraction.
Answer:
principal

9. The elementary colours white light are arranged in order of _______.
Answer:
wave length

10. The band of different colours obtained due to dispersion of white light is called the _______.
Answer:
spectrum

11. ______ first observed the dispersion of white light.
Answer:
Sir Issac Newton

12. Starting from the violet and writing the first latter of the seven colours of the spectrum it is called _______.
Answer:
VIBGYOR

13. The lens which is thinner at the centre and wider at the two edges is known as a _______ lens.
Answer:
convex

14. Lenses are generally of two types, concave and ______.
Answer:
convex

15. If a ray be incident on a convex lens parallel to its principal axis, then the refracted ray through the lens passes through the ______ of the lens.
Answer:
focus.

16. The straight line joins the centres of the spherical surfaces forming the lens is called the _______ axis of the lens.
Answer:
principal

17. The distance of the principal focus from the optical centre of a lens is called its principal ______ length.
Answer:
focal

18. An object place perpendicular to the principal axis of a convex lens will have its image _______ to the principal axis.
Answer:
Perpendicular

19. A transparent body absorbs all the colours of white light except the light of colour of its _______.
Answer:
own

20. Yellow colour is a _______ colour.
Answer:
secondary.

21. The light which consists of only one colour is called ______ light.
Answer:
monochromatic

22. A convex mirror always produces a ______ Image.
Answer:
virtual

23. Refractive index of a medium depends upon ________ of the light.
Answer:
colour.

24. A red flower apprears ______ in green light.
Answer:
black

25. The sky appears blue due to ______ of light.
Answer:
sca tteroing

26. In human eye the image is formed on _______.
Answer:
retina

27. A ________ mirror is used as a shaving mirror.
Answer:
infinity

28. The radius of curvature of a spherical mirror is 20 cm. Its focal length is ______ cm.
Answer:
10

29. ______ In 1841 was the first to give a systematic analysis of formation of images under paraxial approximation.
Answer:
Gauss

30. Only rays inclined at an angle less than about _______ to the principal axis is considered as paraxial rays.
Answer:
10°

31. The radius of curvature of a convex mirror is ______ Its focal length.
Answer:
twice

32. As angle of prism increases, angle of deviation ______.
Answer:
increases

33. When for a particular angle of incidence, the angle of deviation is minimum, the position is known as ______ position of the prism.
Answer:
minimum deviation

34. In case of a rectangular glass slab, the emergent ray is _______ to the incident ray.
Answer:
parallel

35. Refractive index of a gas _______ with increase in temperature.
Answer:
decreases

36. Speed of light in water is lesser than that in air. Hence, air is optically ______ medlum.
Answer:
rarer

37. Magnification produced by a concave lens is always _______.
Answer:
positive

38. If a person walking in a dark room enters into a brightly lit corridor, the pupil of the eye ______.
Answer:
contracts

39. ______ is a hole in the middle of iris.
Answer:
Pupil

40. _______ lens is used as eye-lens in Galllean telescope.
Answer:
Concave

41. When the object is stuated at 2 F₁ (i.e. at twice the distance of focal length) from a convex lens, the image formed is real and ______.
Answer:
inverted

42. When a red’ flower is viewed in green light it appeans _____.
Answer:
black.

43. _____ discovered the dispersion of light by a prism.
Answer:
Newton

44. Among the visible light, _______ coloured light is deviated the least.
Answer:
red

45. ______ are used for studying crystal structure of solids.
Answer:
X-rays

46. ______ rays are used in radio-therapy.
Answer:
Gamma

47. The part of light we can see with our eyes is called _______ spectrum.
Answer:
visible

State whether the following statement is True or False : VSA

1. Concave mirror is used as a rear vlew mirror in cars.
Answer:
False

2. The radius of curvature of a convex mirror is twice its focal length.
Answer:
True

3. The image formed by a convex mirror is inverted and magnified.
Answer:
False

4. Both magnified and diminished image of an object can be formed using a concave mirror.
Answer:
True

5. Speed of light decreases with increase in temperature.
Answer:
False

6. Refractive index of a medium can be less than 1 .
Answer:
False

7. Only the refracting surfaces of a prism need to be transparent.
Answer:
True

8. Myopia is caused due to high converging power of eye-lens.
Answer:
True

9. Cone cells cause the sensation of colour of objects in our eye.
Answer:
True

10. Iris has no colour of its own.
Answer:
False

11. Yellow is referred to as the mean colour.
Answer:
True

12. A rectangular glass slab also produces dispersion of light.
Answer:
False

13. A prism itself produces no colours.
Answer:
True

14. Higher the wave length of light, lower will be its frequency.
Answer:
True

Well structured WBBSE Class 10 Physical Science MCQ Questions Chapter 8.3 Electricity and Chemical Reactions can serve as a valuable review tool before exams.

Electricity and Chemical Reactions Bonding Class 10 WBBSE MCQ Questions

Multiple Choice Questions :

Question 1.
The electrolyte is
(A) Glycerine
(B) Sugar
(C) Sodium chloride
(D) Glucose
Answer:
(C) Sodium chioride

Question 2.
The vessel in which electrolysis takes place is called :
(A) Voltameter
(B) Voltmeter
(C) Calorimeter
(D) Ammeter
Answer:
(A) Voitameter

Question 3.
Which of the following substances is non-metal but conductor :
(A) Nickel
(B) Iron
(C) Silver
(D) Gas carbon
Answer:
(D) Gas carbon

Question 4.
A silver substance is to be gold plated which is to be used as anode:
(A) Pt
(B) Au
(C) Cu
D) Fe
Answer:
(B) Au

Question 5.
What is the volume ratio of produced hydrogen and oxygen from electrolysis of water ?
(A) 1 : 2
(B) 2 : 1
(C) 2 : 3
(D) 1 : 1
Answer:
(B) 2 : 1

Question 6.
Which agent conducts electricity during electrolysis ?
(A) water
(B) ion
(C) atom
(D) molecule.
Answer:
(B) ion

Question 7.
Molter sodium chloride conducts electricity due to the presence of:
(A) free electrons
(B) free ions
(C) free molecules
(D) atoms of sodium and chlorine
Answer:
(B) free ions

Question 8.
An electrolyte :
(A) gives ions only when dissolved in water
(B) gives ions only when electric current is passed
C) has ions even in the solid state
(D) does not give complex ions in solution
Answer:
(C) has ions even in the solid state

Question 9.
The amount of an ion discharged during electrolysis is not directly proportional to:
(A) resistance
(B) time
(C) current
(D) chemical equivalent
Answer:
(A) resistance

Question 10.
Which one of the following solutions will conduct electricity ?
(A) Magnesium chloride in water
(B) Sugar in water
(C) Sugar in ethyl alcohol
(D) lodine in ethyl alcohol
Answer:
(A) Magnesium chloride in water

Question 11.
In the electrolysis of NaCl :
(A) Cl^– ion is oxidised at anode
(B) Cl^– ion is reduced at anode
(C) Cl^– ion is oxidised at cathode
(D) Cl^– ion is neither reduced or oxidised
Answer:
(A) Cl^– ion is oxidised at anode

Question 12.
On the electrolysis of aQuestion solution of sodium sulphate, on cathode, we get :
(A) Na
(B) H₂
(C) SO₂
(D) SO₃
Answer:
(A) Na

Question 13.
On electrolysis a solution of dilute H₂ SO₄ using platinum electrodes, the gas evolved at the anode is :
(A) SO₂
(B) SO₃
(C) O₂
(D) H₂
Answer:
(C) O₂

Question 14.
When a copper wire is placed in solution of AgNO₃, the solution acquires blue colour. This is due to the formation of:
(A) Cu⁺² ions
(B) Cu⁺ ions
(C) soluble complex of copper with AgNO₃
(D) none of these
Answer:
(A) Cu⁺² ions

Question 15.
Flow of current in an electrolyte is due to :
(A) atoms
(B) electrons
(C) ions
(D) none of these
Answer:
(C) ions

Question 16.
Use of electrolysis is :
(A) Electroplating
(B) Electrorefining
(C) Both A And B
(D) none of these
Answer:
(C) Both A And B

Question 17.
Electroplating was discovered by :
(A) Faraday
(B) Arrhenius
(C) Newton
(D) Dalton
Answer:
(A) Faraday

Question 18.
Which of the following is a strong electrolyte :
(A) Ca(NO₃)₂
(B) HCN
(C) H₂ SO₃
(D) NH₄ OH
Answer:
(A) Ca(NO₃)₂

Question 19.
The electroplating with chromium is under taken because :
(A) electrolysis of chromium is easier
(B) chromium can form alloys with other metals
C) chromium gives a protective and decorative coating to the base metal
(D) of high reactivity of chromium metal
Answer:
(C) Chromium gives a protective and decorative conting to the base metal.

Question 20.
Pure water does not conduct electricity because it:
(A) has low boiling point
(B) is neutral
(C) is almost unionised
(D) is readily decomposed
Answer:
(C) is almost unionised

Question 21.
During electrolysis of CuSO₄, the product collected at the anode is:
(A) Oxygen
(B) Hydrogen
(C) Copper
(D) Sulphate
Answer:
(A) Oxygen

Question 22.
During the electrolysis of fused sodium chloride, the anodic reaction is :
(A) reduction of sodium ions
(B) oxidation of sodium ions
(C) reduction of chloride ions
(D) oxidation of chloride ions
Answer:
(D) oxidation of chloride ions

Question 23.
The unit of quantity of electricity is :
(A) volt
(B) coulomb
(C) ampere
(D) ohm
Answer:
(B) coulomb

Question 24.
In electroplating copper with silver, the both solution used is of K[Ag(CN)₂] instead of AgNO₃ because on account of complex formation :
(A) a thin coating of silver is obtained
(B) Ag+ ions are completely removed from the solution
C) expenses on electricity are reduced
(D) availability of Ag+ ions in solution is so reduced that they are not replaced by copper ions.
Answer:
(D) availability of Ag+ ions in solution is so reduced that they are not replaced by copper ions.

Question 25.
For the electroplating of nickel, nickel sulphate is mixed with :
(A) water
(B) nitric acid
(C) boric acid
(D) H₂ SO₄ as electrolyte
Answer:
(C) boric acid

Question 26.
During electrolysis of copper using copper electrodes of copper in solution is :
(A) increased
(B) decreased
(C) unaltered
(D) None of these
Answer:
(C) unaltered

Question 27.
Which one of the following is a non-electrolyte ?
(A) NaCl
(B) HCl
(C) urea
(D) H₂ SO₄
Answer:
(C) urea

Question 28.
Which one is a strong electrolyte ?
(A) NaOH
(B) NH₄ OH
(C) CH₃ COOH
(D) glucose
Answer:
(A) NaOH

Question 29.
In electrolytic solution electricity is conducted by :
(A) electrons
(B) atoms
(C) ions
(D) molecules
Answer:
(C) ions

Question 30.
Electrolysis of CuSO₄ solution using Cu-electrodes, the products at electrodes are :
(A) Cu-at anode
(B) Cu⁺² at anode
(C) H₂ at cathode
(D) O₂ at anode
Answer:
(B) Cu⁺² at anode

Question 31.
Reaction takes place during electrolysis at electrodes are :
(A) oxidation at cathode
(B) reduction at anode
(C) reduction at cathode
(D) no chemical reaction
Answer:
(C) reduction at cathode

Question 32.
Which one is an inert electrode?
(A) copper
(B) iron
(C) platinum
(D) graphite
Answer:
(D) graphite

Question 33.
During the electroplating of a spoon with silver, the reaction taking plac at anode is.
(A) Ag⁺²+2e → Ag
(B) Ag-2 e → Ag⁺²
(C) Ag-e → Ag⁺
(D) Ag⁺+ e → Ag
Answer:
(C) Ag-e → Ag⁺

Question 34.
The reaction that takes place at anode is :
(A) oxidation
(B) reduction
(C) substitution
(D) acid-base
Answer:
(A) oxidation

Question 35.
Which of the following is a weak electrolyte?
(A) CuSO₄
(B) KOH
(C) H₂ SO₄
(D) CH₃ COOH
Answer:
(D) CH₃ COOH

Question 36.
Identify the strong electrolyte
(A) ammonium hydroxide
(B) acetic acid
(C) nitric acid
(D) carbonic acid
Answer:
(C) nitric acid

Question 37.
Choose the wrong statement :
(A) Pure water is a poor conductor of electricity
(B) Cations carry positive charges
(C) Anions move towards anode during electrolysis
(D) Oxidation takes place at the cathode
Answer:
(D) Oxidation takes place at the cathode

Question 38.
11.2 L of a gas is evolved at cathode during electrolysis of water. Amount of gas evolved at anode at the same temperature and pressure is :
(A) 5.6 L
(B) 11.2 L
(C) 22.4 L
(D) 44.8 L
Answer:
(A) 5.6 L

Question 39.
During copper refining which is used as anode?
(A) platinum
(B) pue copper
(C) graphite
(D) impure copper
Answer:
(D) impure copper

Question 40.
Energy conversion during electrolysis is :
(A) chemical to electrical
(B) electrical to chemical
(C) electrical to mechanical
(D) mechanical to electrical
Answer:
(B) electrical to chemical

Fill in the blanks :

1. _______ is a vessel in which electrolysis is carried out.
Answer:
Voltameter.

2. In electrolysis of water, hydrogen accumulates at the cathode and _______ at the anode.
Answer:
oxygen.

3. The decomposition process of electrolytes into ions is known as _______ dissociation.
Answer:
ionic.

4. In electrolyte electrical conduction occurs by migration of _______.
Answer:
ions.

5. An electrolyte is a compound that conducts electricity in fused or solution state and at the same time _______ chemically.
Answer:
decomposes.

6. In the electrolysis, electric current enters the electrolyte solution through the anode and leaves through the _______.
Answer:
cathode.

7. Aluminium is extracted by the electrolysis of a molten mixture of bauxite and _______.
Answer:
cryolyte.

8. In the electrolysis of water, it is found that at the same temperature and pressure _______ olume of oxygen and two volumes of hydrogen are evolved.
Answer:
one.

9. Compounds which in the _______ state or in aqueous solution can conduct electricity and are decomposed chemically yielding new substances are called electrolytes.
Answer:
fused.

10. Mercury is a good conductor of electricity but is not an _______.
Answer:
electrolyte.

11. Rubber is _______ of electricity.
Answer:
non-conductor.

12. In electro-plating, the plating metal is used as _______.
Answer:
cathode.

13. The process of depositing a thin layer of one metal over another metal with the help of an electric current is called _______.
Answer:
electroplating.

14. _______ is a semi-conductor.
Answer:
Silicon.

15. 2 H^⊕ + 2 e →
Answer:
2 H.

16. The aqueous solution of sugar is _______.
Answer:
non-electrolyte.

17. _______ is used as an electrolyte for the electroplating of Nickel.
Answer:
Nickel sulphate (NiSO₄) with boric acid (H₃ BO₃)

18. The aqueous solution of sodium hydroxide is _______.
Answer:
electrolyte.

19. In electrolysis _______ conduct electricity.
Answer:
ions.

20. Between H^⊕ and Al³⁺ _______ ion is discharged first at cathode.
Answer:
H^⊕.

21. Between Br and OH^– _______ ion is discharged first at anode.
Answer:
OH^–

22. Compounds which do not conduct an electric current is aqueous solution or in the molten state are termed as_______.
Answer:
non-electrolytes.

23. The _______ of the total number of molecules of an electrolyte dissociating into free ions is known as the degree of dissociation.
Answer:
fraction.

24. The products formed during electrolysis are deposited or liberated only at the _______.
Answer:
electrodes.

25. _______ changes that occur during electrolysis at the electrodes start as soon as the current is switched on and cease as soon as it is switched off.
Answer:
Chemical.

26. Electrolysis of molten NaCl produces and at cathode _______ and _______ anode respectively.
Answer:
Na, Cl₂

27. With increase of temperature of the electrolytic solution its conductivity will _______.
Answer:
increase

28. Example of strong electrolyte is _______.
Answer:
H₂ SO₄

29. It is the _______ which are responsible for conduction of electricity in electrolytic solution.
Answer:
ions

30. In electroplating with gold the anode used is _______.
Answer:
pure gold plate.

31. During gold plating, the objects to be coated with gold are used as _______.
Answer:
cathode

32. During silver plating the electrolyte used is _______.
Answer:
potassium argentocyanide

33. In case of metals, current is carried by _______.
Answer:
electrons

34. In case of aqueous solution of an electrolyte, current is carried by _______.
Answer:
ions

35. In case of _______ electrolyte, it dissociates completely when dissolved in water.
Answer:
strong

36. In case of _______ electrolyte, it dissociates partially when dissolved in water.
Answer:
weak

37. _______ is connected to the positive terminal of the battery.
Answer:
Anode

38. _______ is connected to the negative terminal of the battery.
Answer:
cathode

39. During electrolysis of a mixture of alumina and cryolite _______ is used to lower the melting point of pure alumina.
Answer:
fluorspar

40. During electrolysis of copper sulphate using copper electrodes, the weight of anode _______.
Answer:
decreases

State whether the following statement is True or False : VSA

1. Little amount of acid is added to water during electrolysis of water.
Answer:
True

2. Through electroplating, a layer of high reactive metal is applied over a low reactive metal is applied over a low reactive metal.
Answer:
False

3. During electrolysis electrolytes conduct electricity through electrons.
Answer:
False

4. Method of electrolysis is utilized during extraction of metals such as aluminium, sodium etc.
Answer:
True

5. During electrolysis of water, hydrogen and Oxygen gas are produced at a volume ratio of 1: 2
Answer:
False

6. Pure water is a good conductor of electricity.
Answer:
False

7. Sodium chloride can conduct electricity in molten state.
Answer:
True

8. During electrolysis, Oxidation takes place at cathode and reduction takes place at anode.
Answer:
False

9. When an electrolyte is dissolved in water, ions ae formed.
Answer:
True

10. When an electrolyte is dissolved in water, ions are formed, hence the solution becomes charged.
Answer:
True