Well structured WBBSE Class 9 Physical Science MCQ Questions Chapter 4.6 Water can serve as a valuable review tool before exams.
Multiple Choice Questions :
Question 1.
The salt which is the cause of hardness of water :
(i) NH4 Cl
(ii) NaNO3
(iii) MgSO4
(iv) K2 SO4
Answer:
(iii) MgSO4
Question 2.
Soap is a salt of :
(i) Acetic acid
(ii) Palmitic acid
(iii) Formic acid
(iv) Nitric acid.
Answer:
(ii) Palmitic acid
Question 3.
Which of the following metals does not react with cold and hot water :
(i) Fe
(ii) K
(iii) Ni
(iv) Ag
Answer:
(iv) Ag
Question 4.
Which of the following is soft water:
(i) rain water
(ii) river water
(iii) tube well water
(iv) sea water
Answer:
(i) rain water
Question 5.
The salt which is the cause of temporary hardness :
(i) NaHCO3
(ii) NaCl
(iii) Ca(HCO3)2
(iv) MgSO4
Answer:
(iii) Ca(HCO3)2
Question 6.
Which of the following metals reacts easily with water at ordinary temperature :
(i) Ca
(ii) Zn
(iii) Cu
(iv) Ag
Answer:
(i) Ca
Question 7.
Tube well water becomes brown due to :
(i) Ca(HCO3)2
(ii) Fe(HCO3)2
(iii) MgSO4
(iv) MgCl2
Answer:
(ii) Fe(HCO3)2
Question 8.
D2 O reacts with CaC2 to form :
(i) C2 D2
(ii) CaD2
(iii) Ca2 D2 O
(iv) CD2
Answer:
(i) C2 D2
Question 9.
Permutit is regenerated by passing :
(i) 10% NaOH solution
(ii) 10% NH4 Cl solution
(iii) 10% NaCl solution
(iv) none of these
Answer:
(iii) 10% NaCl solution.
Question 10.
If 1 lit. water contains 0.001 mol MgSO4. What will be the hardness of water?
(i) 100 ppm
(ii) 200 ppm
(iii) 500 ppm
(iv) 150 ppm
Answer:
500 ppm
Question 11.
Water has high boiling point because :
(i) specific heat of water is high
(ii) heat of dissociation is high
(iii) presence of hydrogen bonding
(iv) molecules weight is low
Answer:
Presence of hydrogen bonding.
Question 12.
Anion exchange resin is regenerated by passing :
(i) dilute NaCl solution
(ii) dilute H2 SO4 solution
(iii) dilute HNO3 solution
(iv) dilute NaOH solution
Answer:
dilute NaOH solution
Question 13.
When hard water is passed through zeolite, the Na (present in zeolite) is exchanged by :
(i) OH–
(ii) Ca2+
(iii) \(\mathrm{SO}_4^{2-}\)
(iv) H+
Answer:
Ca2+
Question 14.
Water is oxidised to oxygen by :
(i) ClO2
(ii) KMnO4
(iii) H2 O2
(iv) F2
Answer:
F2
Question 15.
Sodium promptly reacts with water at ordinary temperature to form sodium hydroxide and what ?
(i) oxygen
(ii) nitrogen
(iii) chlorine
(iv) hydrogen
Answer:
hydrogen
Question 16.
Which state of water provides medium of life ?
(i) Solid
(ii) liquid
(iii) vapour
(iv) gas
Answer:
liquid.
Question 17.
Which property of water controls environmental temperature ?
(i) specific heat capacity
(ii) Latent heat of vaporisation
(iii) density
(iv) surface tension
Answer:
Specific heat capacity
Question 18.
Air obtained from dissolved air in water contain oxygen and nitrogen respectively in what percentage?
(i) 21% O2, 78% N2
(ii) 17% O2, 83% N2
(iii) 33% O2, 66% N2
(iv) 66% O2, 33% N2
Answer:
33% O2, 66% N2
Question 19.
What is the prescribed limits of pH of potable water?
(i) 4.5
(ii) 6.5-8.5
(iii) 1.5-4.5
(iv) 8.5-9.5
Answer:
6.5-8.5
Question 20.
Which of the following ions responsible for hardness of water?
(i) Fe2+
(ii) Na+
(iii) Cr3+
(iv) Mn2+
Answer:
Fe2+
Fill in the blanks :
1. _______ reacts with water at ordinary temperature.
Answer:
Calcium
2. Soft water readily forms lather with _______.
Answer:
soap
3. Water of sea, river are examples of _______ water.
Answer:
hard
4. By using _______ water thermal plants can cut water requirements by about 98%.
Answer:
recycled
5. Depletion of oxygen dissolved in water due to enhanced growth of algae is called _______.
Answer:
eutrophication
6. Elements having greater tendency to gain electrons from their solution are called _______ elements.
Answer:
electronegative
7. Deionised water contains only H+ cation and _______ anion.
Answer:
OH–
8. A more reactive metal displaces a _________ reactive metal from the latter’s solution.
Answer:
less
9. Cation-exchanger resins contain COOH, _______ radicals.
Answer:
SO3 H
10. Temporary hardness of water is due to presence of soluble _______
Answer:
bicarbonates
11. Permanent hardness of water is due to presence of dissolved chloride and _______ salts of Ca and Mg.
Answer:
sulphate
12. The class of water that does not easily form _______ with soap is called hard water.
Answer:
lather
13. The class of water that easily form lather with soap is called ______ water.
Answer:
soft
14. Water is a _______ solvent.
Answer:
versatile
15. Removal of both temporary and permanent hardness is done by ______ process.
Answer:
ion exchange
16. Removal of temporary hardness of water is done by _______.
Answer:
boiling
17. De-ionised water is made by _______.
Answer:
de-ioniser
18. Among river water, rain water and tubewell water, _______ is soft water.
Answer:
rain water
19. Cu does not react with _______ at ordinary temperature.
Answer:
water
20. The 97 % water of the total amount of earth’s water is called _______ water.
Answer:
underground
21. _______ is the chemical name of zeolite.
Answer:
Sodium aluminosilicate (Na2 O, Al2 O3, 3 SiO2, 2 H2 O)
22. The permissible limit of arsenic in drinking water is _______.
Answer:
0.05 mg / L
23. Amberlite IR-120 is a useful _______ exchanger.
Answer:
cation
24. RSO3 H is a ______ exchanger resin.
Answer:
cation
25. If pressure on the surface of water is increased, its boiling point and freezing point ______.
Answer:
increases, decreases.
26. Temporary hard water contains ______ salt of calcium, magnesium and iron.
Answer:
hydrogen carbonate
27. RNH3+ OH – is ______ exchanger resin.
Answer:
anion
Well structured WBBSE Class 9 Physical Science MCQ Questions Chapter 3 Matter: Structure and Properties can serve as a valuable review tool before exams.
Multiple Choice Questions :
Question 1.
atmospheric pressure is measured by :
(i) hygrometer
(ii) pyrometer
(iii) Barometer
(iv) spherometer
Answer:
Barometer
Question 2.
Construction of a submarine is based on :
(i) Archimedes’ principle
(ii) Bernoulli’s theorem
(iii) Pascal’s law
(iv) Boyle’s law
Answer:
Archimedes’ principle
Question 3.
Why is the dam of water reservoir is thick at the bottom?
(i) quantity of water increases with depth
(ii) density of water increases with depth
(iii) pressure of water increases with depth.
(iv) temperature of water increases with depth.
Answer:
The pressure of water increases with depth.
Question 4.
A wooden block is taken to the bottom of a deep, calm lake and then released. it rises up with a :
(i) constant acceleration
(ii) decreasing acceleration
(iii) constant velocity
(iv) decreasing velocity
Answer:
Constant acceleration
Question 5.
A capillary tube made of glass is dipped into mercury. Then
(i) mercury rises in the capillary tube
(ii) mercury falls in the capillary tube
(iii) mercury rises and flows out of capillary tube
(iv) mercury neither rises nor falls in the capillary tube
Answer:
Mercury falls in the capillary tube
Question 6.
If the diameter of a capillary tube be doubled then the height of the liquid that will rise is :
(i) twice
(ii) half
(iii) same as earlier
(iv) none of these.
Answer:
Half
Question 7.
Two pieces of glass plates one upon the other with a little water in between them cannot be separated easily because of :
(i) inertia
(ii) pressure
(iii) surface tension
(iv) viscosity
Answer:
Surface tension
Question 8.
There is dip in the capillary tube when the angle of contact θ is :
(i) θ = 90°
(ii) θ = 0°
(iii) θ > 90°
(iv) θ < 90° but not zero
Answer:
θ < 90° but not zero
Question 9.
The rise of liquid in a capillary tube has a meniscus. If the angle of contact be 90°, the shape of the meniscus is :
(i) concave
(ii) convex
(iii) flat
(iv) none of the above
Answer:
Flat
Question 10.
In Bernoulli’s theorem, which of the following is conserved ?
(i) mass
(ii) linear momentum
(iii) energy
(iv) angular momentum
Answer:
Energy
Question 11.
The gale blows over a house. The force due to gale on the roof is :
(i) in the direction downward
(ii) in direction upward
(iii) zero
(iv) in the horizontal direction.
Answer:
In direction upward
Question 12.
To calculate the flow of a liquid, which of the following is used?
(i) Stoke’s law
(ii) Bernoulli’s theorem
(iii) Poiseuille’s law
(iv) Conservation of pressure
Answer:
Poiseuille’s law
Question 13.
Scent sprayer is based on :
(i) Charles’s law
(ii) Archimedes’ principle
(iii) Boyle’s law
(iv) Bernoulli’s theorem.
Answer:
Bernoulli’s theorem
Question 14.
In old age arteries carrying blood in the human body become narrow resulting in an increase in the blood pressure. This follows from
(i) Pascal’s law
(ii) Stoke’s law
(iii) Bernoullis’ principle
(iv) Archimede’s principle
Answer:
Bernoulli’s principle
Question 15.
On which of the following the terminal velocity of a solid ball in a viscous fluid is independent?
(i) area of cross-section
(ii) height of the liquid
(iii) density of the both
(iv) density of the liquid
Answer:
Height of the liquid
Question 16.
A body of weight mg is hanging on a strain, which extends its length by 1. The work done in extending the string is :
(i) mgl
(ii) mgl / 2
(iii) 2 mgl
(iv) none of these
Answer:
mgl / 2
Question 17.
According to Hooke’s law of elasticity, if stress is increased the ratio of stress to strain :
(i) increases
(ii) decreases
(iii) becomes zero
(iv) remains constant
Answer:
Remains constant
Question 18.
S.I. unit of pressure is
(i) pascal
(ii) Kgfm-2
(iii) atmosphere
(iv) none of these
Answer:
pascal
Question 19.
upthrust depends upon –
(i) volume
(ii) density
(iii) g
(iv) all of these
Answer:
all of these
Question 20.
If the density of the object placed in a liquid to the density of the liquid, the object will –
(i) float wholly immersed
(ii) float half immersed
(iii) sink
(iv) float completely above the liquid
Answer:
float wholly immersed
Question 21.
Atmospheric pressure is measured by –
(i) hydrometer
(ii) barometer
(iii) sonometer
(iv) ammeter
Answer:
barometer.
Question 22.
Relative density s of a substance is related to the density of the substance ρ and density of water at 40C d as –
(i) s = ρ × d
(ii) \(\mathrm{s}=\frac{d}{\rho}\)
(iii) \(\frac{\rho}{d}\)
(iv) \(\frac{1}{\rho d}\)
Answer:
\(\frac{\rho}{d}\)
Question 23.
SI unit of surface tension is
(i) Nm
(ii) kgfm-1
(iii) mN-1
(iv) Nm-1
Answer:
Nm-1
Question 24.
The terminal velocity of a spherical body depends on
(i) radius of the body
(ii) density of the medium
(iii) viscosity of the medium
(iv) all of these
Answer:
all of these
Question 25.
Bernoulli’s theorem is based on conservation of –
(i) mass
(ii) mass and energy
(iii) energy
(iv) none of these
Answer:
energy.
Question 26.
With increase in temperature, the elasticity of a material
(i) increases
(ii) decreases
(iii) remains unchanged
(iv) nothing can be said
Answer:
decreases
Question 27.
The solids if break soon after crossing elastic limit are called
(i) ductile
(ii) brittle
(iii) malleable
(iv) plastic
Answer:
brittle
Fill in the blanks :
1. The word fluid comes from a Latin word _______.
Answer:
Fluere (meaning ‘to flow’)
2. The branch of physics which deals with fluid at rest is called _______.
Answer:
Hydrostatics
3. The branch of physics which deals with fluid in motion is called _______.
Answer:
Hydrodynamics
4. Specific gravity of a substance is the ratio of the density of a substance to the density of _______ at 4°C.
Answer:
Water
5. In CGS system, the density of a substance is numerically _____ its specific gravity.
Answer:
Equal
6. The unit of pressure in SI is ______.
Answer:
Pascal (Nm-2)
7. The liquid pressure is a ______ quantity.
Answer:
Scalar
8. Archimede’s principle does not hold when the body is in ______ condition.
Answer:
Weightless
9. When the weight of the body is greater than the weight of the liquid displaced, then the body ______.
Answer:
Sinks
10. Condition of floatation of a body is such, that the weight of the floating body must be ______ to the weight of the liquid dispiaced.
Answer:
Equal
11. If the density of the body be equal to the density of the liquid, the body ______ completely immersed any where in the liquid.
Answer:
Floats
12. The height of a water barometer is ______.
Answer:
10.33 m
13. The forces between the molecules of substances are called ______ forces.
Answer:
Inter-molecular
14. The unit of surface tension in SI system is : ______.
Answer:
Newton per metre (Nm-1)
15. Rain drops attain ______ shape to acquire minimum surface area.
Answer:
Spherical
16. A tube with a very fine uniform bore throughout its length called a ______ tube.
Answer:
Capillary
17. A towel soaks water on account of ______ action.
Answer:
Capillary
18. Antiseptics have very ______ surface tension, so that can spread quickly.
Answer:
Low
19. The relative viscosity of a liquid is the ratio of viscosity of a liquid to viscosity of ______.
Answer:
Water
20. The terminal velocity of a sphere varies directly as the square of the ______ of it.
Answer:
Radius
21. The viscosity of a liquid ______ with increase in temperature.
Answer:
Decreases
22. Reynold’s number is the ratio of the inertial force per unit area to ______ force per unit area for a flowing iluid.
Answer:
Viscous
23. The deep water runs ______ in a river.
Answer:
Slow
24. The dimensional formula of stress is ______.
Answer:
[ML-1 T-2]
25. The fractional change in the length, volume or shape of a body relative to that in its original configuration is a measure of the ______.
Answer:
Strain
26. The deformation of an elastic body is directly proportional to the applied force within ______ limit.
Answer:
Elastic
27. The normal force exerted by fluid on any surface in contact with its, called ______.
Answer:
thrust
28. The liquid ______ its own level.
Answer:
finds
29. A ______ is an instrument for measuring the pressure of the atmosphere.
Answer:
barometer.
30. A siphon acts under ______ pressure.
Ans,
atmospheric
31. The upward thrust which any fluid exerts upon a body partly or completely immersed in it, is called its ______.
Answer:
buoyancy
32. Relative density is a pure ______ having no unit.
Answer:
number
33. Surface tension is a ______ quantity.
Answer:
scalar
34. The critical velocity is fixed for a fluid for a given ______.
Answer:
temperature
35. Bernoulli’s theorem is based on principle of conservation of ______.
Answer:
energy
36. The elasticity of a material is ______ on hammering it.
Answer:
increased
Well structured WBBSE Class 9 Physical Science MCQ Questions Chapter 4.5 Separation of Mixtures can serve as a valuable review tool before exams.
Multiple Choice Questions :
Question 1.
Which metal is lighter than water ?
(i) Calcium
(ii) Mercury
(iii) Sodium
(iv) Gold
Answer:
Sodium
Question 2.
Which non-metal exists in liquid state at room temperature?
(i) Mercury
(ii) Bromine
(iii) Carbon
(iv) Sulphur
Answer:
Bromine
Question 3.
Which natural element is hardest ?
(i) Fullerine
(ii) Iron
(iii) Gold
(iv) Diamond
Answer:
Diamond
Question 4.
Name a substance whose properties are intermediate between metal and non-metal ?
(i) Germenium
(ii) Potassium
(iii) Iron
(iv) Carbon
Answer:
Germenium
Question 5.
Which gas has the smell of rotten egg?
(i) Ammonia
(ii) Sulphuretted hydrogen
(iii) Carbon dioxide
(iv) Oxygen
Answer:
Sulphuretted hydrogen.
Question 6.
What is the nature of aqueous solution of NaCl ?
(i) Acidic
(ii) Alkaline
(iii) Neutral
(iv) None of these.
Answer:
Neutral.
Question 7.
Cite an example where both physical and chemical changes occur ?
(i) Incomplete burning of candle.
(ii) Burning of a magnesium ribbon
(iii) Slaking of lime
(iv) Melting of ice.
Answer:
Incomplete burning of candle.
Question 8.
Name a non-metal that conducts heat and electricity ?
(i) Graphite
(ii) Sulphur
(iii) Diamond
(iv) Nitrogen
Answer:
Graphite
Question 9.
MnO2 is a catalyst :
(i) positive
(ii) negative
(iii) both positive and negative
(iv) none of these
Answer: Positive
Question 10.
Heating of a platinum wire is a :
(i) physical change
(ii) chemical change
(iii) both physical and chemical change
(iv) none of these.
Answer:
Physical change
Question 11.
The boiling point of water is :
(i) 100° C
(ii) -100° C
(iii) 0° C
(iv) 78° C
Answer:
100° C
Question 12.
Which catalyst is used to prepare oxygen from KClO3 ?
(i) MnO
(ii) MnO2
(iii) Mn3 O4
(iv) V2 O5
Answer:
MnO2
Question 13.
The method to separate sugar from its equeous solution a –
(i) evaporation
(ii) distillation
(iii) sedimentation
(iv) centrifugation
Answer:
Evaporation
Question 14.
lodine and ethanol can be separated by –
(i) filtration
(ii) evaporation
(iii) distillation
(iv) fractional distillation
Answer:
distillation
Question 15.
Mixture of carbon tetra-chloride and water are separated by using –
(i) funnel
(ii) separating funnel
(iii) breaker
(iv) fractionating column.
Answer:
separating funnel
Question 16.
Boiling point of a liquid –
(i) decreases with increase of pressure
(ii) boiling point has no effect on pressure
(iii) increases with increase of pressure
(iv) do not always increase with increase of pressure.
Answer:
Increases with increase of pressure.
Question 17.
The components of crude oil can be separated by –
(i) fractional distillation
(ii) distillation
(iii) fractional crystallisation
(iv) none of these
Answer:
fractional distillation.
Fill in the blanks :
1. Quick lime when treated with water converts to _______ lime.
Answer:
slaked
2. Graphite is _______ to touch.
Answer:
slippery
3. NH4 Cl treated with NaOH liberates _______ gas.
Answer:
ammonia
4. Rusting of iron is a _______ change.
Answer:
chemical
5. Both physical and chemical changes occur in burning of _______.
Answer:
candle
6. _______ is a liquid non-metal.
Answer:
Bromine
7. Odour of _______ is pungent.
Answer:
ammonia
8. _______ is a metalloid.
Answer:
Arsenic/Antimony
9. Snow at the base of a glacier melts due to its heavy _______.
Answer:
weight
10. _______ is a soft metal.
Answer:
Sodium
11. Colour of copper suiphate crystal is _______.
Answer:
blue
12. Aqueous solution of oxides of some solid _______ are acidic.
Answer:
non-metals
13. Being non-metal _______ conducts electricity.
Answer:
graphite
14. Water is added to conc. H2SO4. This is a _______ change.
Answer:
physical
15. _______ are typically brittle.
Answer:
Non-metals
16. _______ shows the characteristics of both metais and non-metals.
Answer:
Metalloids
17. _______ is insoluble in water but soluble in carbon disulphide.
Answer:
Sulphur.
18. Heating of platinum wire is an example of _______ change.
Answer:
physical
19. Chemical change is _______.
Answer:
permanent
20. Copper sulphate and sulphur are identified by _______.
Answer:
solubility
21. Silver nitrate solution is added to sodium chloride solution to give a curdy white precipitate; the precipitate can be separated from the mixture by a process called _______.
Answer:
filtration.
22. Glycerol is distilled under reduced pressure to avoid _______.
Answer:
evaporation
23. The suspension of chalk in water can be separated by _______.
Answer:
decomposition.
24. Kerosene is lighter and immiscible in water, they can be separated by using _______.
Answer:
separating funnel.
Well structured WBBSE Class 9 Physical Science MCQ Questions Chapter 4.4 Acids, Bases and Salts can serve as a valuable review tool before exams.
Multiple Choice Questions :
Question 1.
Which element is present in all acids ?
(i) Hydrogen
(ii) Oxygen
(iii) Carbon
(iv) Nitrogen
Answer:
Hydrogen
Question 2.
ZnO is –
(i) acidic
(ii) basic
(iii) amphoteric
(iv) neutral oxide
Answer:
amphoteric
Question 3.
The weak acid is
(i) HCl
(ii) HNO3
(iii) H2 SO4
(iv) H2 CO3
Answer:
H2 CO3
Question 4.
Aqueous solution of P2 O5 is
(i) HPO3
(ii) H3 PO4
(iii) H3 PO3
(iv) H3 PO2
Answer:
H3 PO4
Question 5.
Methyl orange is a/an ___
(i) base
(ii) alkali
(iii) indicator
(iv) oxide
Answer:
indicator
Question 6.
Minimum quantity of an indicator used in neutralisation reaction is ____
(i) 5 mL
(ii) 5.2 mL
(iii) 5.5 mL
(iv) 2-3 drops
Answer:
2-3 drops
Question 7.
The aqueous solution of bases turn red litmus into ____
(i) blue
(ii) colourtess
(iii) violet
(iv) yellow
Answer:
blue
Question 8.
NaCl is a/an ____
(i) normal
(ii) acid
(iii) basic
(iv) complex salt
Answer:
normal
Question 9.
The strong acid is _____
(i) H2 SO4
(ii) H2 CO3
(iii) H3 PO4
(iv) CH3 COOH
Answer:
H2 SO4
Question 10.
Caustic soda is a/an _______
(i) salt
(ii) weak base
(iii) strong base
(iv) acid
Answer:
strong base
Question 11.
Sulphuric acid is a/an _________
(i) inorganic acid
(ii) organic acid
(iii) weak acid
(iv) hydracid
Answer:
inorganic acid
Question 12.
Disodium hydrogen phosphate is a/an ______
(i) normal salt
(ii) basic salt
(iii) acid salt
(iv) double salt
Ans.
acid salt
Question 13.
Which of the following compounds is used to prepare vanishing colour
(i) NH4 OH
(ii) NaOH
(iii) Ca(OH)2
(iv) KOH
Answer:
NH4 OH
Question 14.
Na2 SO4 is a/an ____
(i) normal salt
(ii) acid sait
(iii) basic salt
(iv) complex salt
Answer:
normal salt
Question 15.
Indicator used for neutralisation reaction of H2 SO4 and NaOH is _____
(i) methyl orange
(ii) phenolphthalein
(iii) litmus
(iv) any indicator
Answer: any indicator
Question 16.
The colour of phenolphthalein in dilute sulphuric acid solution becomes –
(i) red
(ii) yellow
(iii) blue
(iv) colourless
Answer:
colourless
Question 17.
The colour of methyl orange in acidic solution becomes –
(i) red
(ii) yellow
(iii) blue
(iv) orange
Answer:
red
Question 18.
Sulphuric acid contains
(i) 1
(ii) 2
(iii) 3
(iv) 4 replaceable hydrogen atom/atoms by a metal.
Answer:
2
Question 19.
Ammonia is
(i) an acid
(ii) a base
(iii) a salt
(iv) none of these
Answer:
a base
Question 20.
The acidity of CaO is ___
(i) 1
(ii) 2
(iii) 3
(iv) 4
Answer:
2
Question 21.
The basicity of hydrochloric acid is
(i) 1
(ii) 2
(iii) 3
(iv) 4
Answer:
1
Question 22.
Phosphoric acid is a –
(i) monobasic acid
(ii) dibasic acid
(iii) tribasic acid
(iv) none of these
Answer:
tribasic acid
Question 23.
An aqueous solution turns blue litmus solution into red. Excess addition of which of the following solution to the above solution reverse the change –
(i) HCl solution
(ii) vinegar solution
(iii) H2 SO4 solution
(iv) caustic soda solution
Answer:
caustic soda solution
Question 24.
Which of the following substance change the colour of pH paper to greenish – blue ?
(i) common salt
(ii) vinegar
(iii) an antacid
(iv) orange juice
Answer:
An antacid
Question 25.
To protect tooth decay you are advised to brush your teeth regularly, the nature of commonly used paste is –
(i) neutral
(ii) acidic
(iii) basic
(iv) corrosive
Answer:
Basic
Question 26.
If you soak a pH paper into gastric juices, it will indicate a pH value of –
(i) more than 7
(ii) less thati 7
(iii) equal to 7
(iv) less than 1
Answer:
less than 7
Question 27.
Which of the following is responsible for acid rain ?
(i) N2
(ii) CH4
(iii) SO2 and NO2
(iv) H2
Answer:
SO2 and NO2
Fill in the blanks :
1. An acidic oxide is called _______ of the acid, which forms with water.
Answer:
anhydride
2. An oxide is a ______ of oxygen formed with another element.
Answer:
compound
3. ______ oxides are some metallic oxides which behave both as an acidic and a basic oxide.
Answer:
Amphoteric
4. CO, NO are examples of _____ oxide.
Answer:
neutral
5. Basic oxides which are soluble in water produce _____ when they are disssolved in water.
Answer:
alkalis
6. A base in general is an oxide or hydroxide of a ____ and when reacts with an acid produces _____ and water.
Answer:
Metal, salt
7. _____ is a process in which acids and alkalis in equivalent quantities react in their aqueous solutions to produce salt and water.
Answer:
Neutralisation
8. An acid salt is produced when insufficient quantity of a base reacts with a ______ acid.
Answer:
polybasic
9. Normal salts are formed by the complete replacement of the replaceable ______ atoms from an acid molecule by a suitable substance.
Answer:
hydrogen
10. Indicators are some weak organic acids or bases which indicate distinctive _____ in acid, alkali and neutral solutions.
Answer:
colours
11. Substances with a pH value below 7 are _____
Answer:
acidic
12. The aqueous solution of a base makes _____ litmus blue.
Answer:
red
13. The colour of methyl orange in acid medium is _____ and that in alkaline medium is –
Answer:
Pinkish-red, Yellow
14. An aqueous solution of an acid turns ______ litmus into red.
Answer:
blue
15. pH scale is a scale that runs from ____ to _____.
Answer:
0, 14
16. Na3 PO4 is a _____ salt.
Answer:
normal
17. The substance used to determine the end point of neutralisation of an acid and a base is called _____.
Answer:
indicator
18. Al2 O3 is an _____ oxide.
Answer:
amphoteric
19. H2 O is a ______ oxide.
Answer:
neutral
20. Pb(OH) NO3 is a ______ salt.
Answer:
basic
21. HCN is hydracid but H2 SO3 is _____.
Answer:
oxyacid
22. Concentrated _______ is a strong oxidising acid.
Answer:
H2 SO4
23. An aqueous solution of acid must contain _____ ion.
Answer:
H+
24. The formula of permanganic acid is _____.
Answer:
HMnO4
25. P2 O5 is an _____ oxide.
Answer:
acidic
26. Na2 HPO4 is an_____ salt.
Answer:
acid
27. K4 [Fe(CN)6] is a _____ salt.
Answer:
complex
28. Acetic acid is known as _____.
Answer:
Vinegar
29. Acids have a ______ taste.
Answer:
sour
30. Tooth enamel is made of ____.
Answer:
Ca3 (PO4)2
31. pH value of pure water is ______.
Answer:
0
32. Exact pH value of acid rain is _____.
Answer:
5.6
33. ______ indicator is a such indicator which can determine the strength of solution.
Answer:
universal
Detailed explanations in West Bengal Board Class 9 Physical Science Book Solutions Chapter 4.3 Solution offer valuable context and analysis.
Very short answer type questions
Question 1.
Write down the name of an inorganic and an organic solvent.
Answer:
Name of an inorganic solvent: water Name of an organic solvent: benzene
Question 2.
Write down the name of a substance whose solubility remains almost the same with rise of temperature.
Answer:
Solubility remains almost the same with rise of temperature: Sodium chloride (NaCl).
Question 3.
Write down the name of a substance whose solubility decreases with the increase of temperature.
Answer:
Solubility decreases with the increase of temperature: Calcium sulphate (CaSO4).
Question 4.
Write down the name of a substance whose solubility increases tremendously with the increase of temperature.
Answer:
Solubility increases tremendously with the increase of temperature: e.g. Potassium nitrate (KNO3)
Question 5.
What is the unit of solubility ?
Answer:
Solubility has no unit.
Question 6.
Which gas is soluble in soda water ?
Answer:
Carbon dioxide (CO2) is soluble in soda water.
Question 7.
Give an example of a drying agent.
Answer:
Drying agent : concentrated H2SO4.
Question 8.
Give a common example of colloidal solution.
Answer:
Common example of colloidal solution : milk.
Question 9.
What are the components of a colloidal solution ?
Answer:
Components of a colloidal solution :
Question 10.
Give one example of a salt having water of crystallisation.
Answer:
Example of a salt having water of crystallisation :
Blue vitriol (CuSO4. 5H2O)
Question 11.
Mention one particulate matter in air that causes its pollution.
Answer:
Particulate matter in air that causes its pollution : Fine particules of dust.
Question 12.
What are the sizes of the colloid particles?
Answer:
Sizes of the colloid particles : 10-5 cm to 10-7 cm in diameter.
Question 13.
State whether solution is a mixture or compound.
Answer:
Solution is a mixture.
Question 14.
Why edible salt (NaCl) becomes moist in the rainy season?
Answer:
Edible salt (NaCl) becomes moist in rainy season due to the presence of deliquescent MgCL2 6H2O as impurity in it.
Question 15.
Name an efflorescent substance.
Answer:
Efflorescent substance: Washing soda (Na2CO3.10H2O)
Question 16.
Name a deliquescent substance.
Answer:
Deliquescent substance : Calcium chloride (CaCl2)
Question 17.
What happens if a saturated solution is cooled?
Answer:
The cooled solution sheds the excess solute as crystals.
Question 18.
What is the effect of increase of pressure on the solublilty of a gas In water?
Answer:
Increase of pressure increases solubility of a gas.
Question 19.
What is the effect of increase of pressure on the sotubility of a solid in water?
Answer:
Increase of pressure does not cause any change of solubility of a solid in water.
Question 20.
What is occlusion?
Answer:
Hydrogen get dissolved in spongy palladium in some similar metals. This phenomenon is called occlusion.
Question 21.
What is TEL?
Answer:
Tetra ethyl lead (TEL).
Question 22.
What is epsome salt?
Answer:
Epsome salt : MgSO4, 7H2O
Question 23.
What is SPM?
Answer:
Suspended particulate matter (SPM)
Question 24.
What do you mean by smog ?
Answer:
Smog is fog containing smoke.
Question 25.
How a saturated solution may be made unsaturated ?
Answer:
A saturated solution may be made unsaturated either by :
Question 26.
State the biological importance of dissolved O2 in water.
Answer:
Aquatic plants and animals can take oxygen for their respiration.
Question 27.
What is the effect of temperature on the solubility of KNO3 and CasO4 ?
Answer:
Solubility of KNO3 increases with rise of temperature.
Solubility of CaSO4 decreases with rise of temperature.
Question 28.
How can you increases the solubility of a given volume of gas in water ?
Answer:
An increase of pressure on the surface of water causes increase of solubility of gas in water.
Question 29.
Why does the CO2 gas rapidly bubbles out when the lid of its bottle is opened ?
Answer:
CO2 gas rapidly bubbles out when the lid of its bottle is opened because on opening the lid the pressure on the solution suddenly decreases.
Question 30.
Which solution is more concentrated : 10g/L NaOh or 10 molar NaOH solution ?
Answer:
10 molar NaOH solution.
Short Answer Type Question
Question 1.
What is a solution ?
Answer:
Solution : A solution (or true solution) is a uniformly homogeneous mixture of two or more substances whose relative proportions may be varied upon a certain limit.
Question 2.
Name the different types of solution known to you in respect of concentration.
Answer:
Classification of solution : Solutions are classified into three types based on concentration at a certain temperature. These are :
Question 3.
What is an unsaturated solution ?
Answer:
Unsaturated solution : At a particular temperature, an unsaturated solution is one in which the solvent is capable of dissolving further amount of the solute.
Question 4.
What is a saturated solution ?
Answer:
Saturated solution : A saturated solution at a particular temperature is one in which the amount of the solvent has reached its maximum capacity of dissolving the solute.
Question 5.
What is a supersaturated solution ?
Answer:
Supersaturated solution : A supersaturated solution is one, in which the amount of the solvent has dissolved more amount of the solute than is necessary to make a saturated solution at the particular temperature.
Question 6.
How can you detect a saturated sugar solution ?
Answer:
Detection for saturated sugar solution : To the given solution, some amount of sugar is added into the solution and stirred. If the added sugar does not dissolve, the solution is said to be a saturated solution at that temperature.
Question 7.
How can you detect an unsaturated sugar solution ?
Answer:
Detection for unsaturated sugar solution : To the tested solution some sugar is added and stirred. If the sugar readily dissolves, the given solution is said to be an unsaturated solution.
Question 8.
What do you mean by solute ?
Answer:
Solute : The substances which are present in smaller quantities and gets dissolved are called solute.
Question 9.
What is meant by solvent ?
Answer:
Solvent : The medium in which the solutes are uniformly dispersed through dissolution is called the solvent.
Question 10.
Define a colloid or colloidal solution.
Answer:
Colloid or colloidal solution : A colloid or colloidal solution is a stable heterogeneous solution consisting of finely divided particles of a substance (of the size of 10-5 cm to 10-7 cm in diameter) uniformly dispersed in a continuous medium.
Question 11.
What do you mean by solubility ?
Answer:
Solubility : Solubility of a given solute in a solvent is defined as the weight in grams of the solute dissolved in 100 grams of solvent so as to saturate the solution at a given temperature.
Question 12.
What is meant by ‘solubility is dependent on temperature’ ?
Answer:
Solubility is dependent on temperature: It means, in general, solubility of a solid in a liquid solvent increases with increasing temperature and decreases with decreasing temperature. This rule is not obeyed in some cases.
Question 13.
What are the effects of temperature on solubility of CaSO4) KNO4, NaCl ?
Answer:
Effect of temperature on solubility of CaSO4, KNO3, NaCl.
Solubility of CaSO4 decreases with increasing temperature.
Solubility of KNO3 increases rapidly with rise of temperature.
Solubility of NaCl remains almost unchanged with rise of temperature
Question 14.
What do you mean by ‘dispersed phase’ and ‘dispersion medium’ ?
Answer:
Question 15.
Define crystal.
Answer:
Crystal : Crystals are homogeneous solid particles bounded by plane surfaces arranged symmetrically and meeting at sharp edges and forms a definite three-dimenstional geometrical shape.
Question 16.
What do you mean by crystallisation ?
Answer:
Crystallisation : Crystallisation is a process by which crystals of a substance are obtained from its solution.
Question 17.
What is water of crystallisation ?
Answer:
Water of crystallisation : The fixed number of water molecules that are associated with a crystal as an integral part of the constitution of the crystal is called water of crystallisation.
Example : Blue vitriol (CuSO4, 5H2O) has five molecules of water of crystallisation.
Question 18.
What is meant by efflorescent substance ?
Answer:
Efflorescent substance : Efflorescent substances are those which crumble to powder when exposed to air due to partial or total loss of water molecules present in their crystalline structures.
Example : Washing soda (Na2CO3, 10H2O)
Question 19.
What do you mean by deliquescent substance ?
Answer:
Deliquescent substance : Deliquescent substances are those solid which when exposed to atmosphere form concentrated solution dissolving in the moisture absorbed by them from air.
Example : Calcium chloride (CaCl2).
Question 20.
What happens if a saturated solution is cooled ?
Answer:
If a hot saturated solution is cooled, the capacity of holding solute by the solution decreases. The cooled solution sheds the excess solute as crystals.
Question 21.
What are the effects of increase of pressure on the solubility of a gas and a solid solute in water ?
Answer:
Increase of pressure increases solubility of a gas in water ; increase of pressure does not cause any change of solubility of a solid in water.
Question 22.
Why is temperature mentioned in defining solubility ?
Answer:
In defining solubility of a substance, temperature is to be mentioned, because, with change of temperature solubility of most of the substances changes.
Question 23.
Why is a solution kept stirred continuously during its preparation ?
Answer:
It is done to mix well the saturated and the unsaturated portions of the solution to bring about homogeneity of the solution.
Question 24.
What are hygroscopic substances ?
Answer:
Hygroscopic substances : Certain substances exposed to air absorb moisture from air but are not dissolved in the absorbed water. These substances are called hygroscopic substances.
Question 25.
What are drying agents ?
Answer:
Drying agents : Some substances have the property to absorb moisture from moisturous bodies present nearby. These substances are called drying agents.
Example : Concentrated H2SO4, Phosphorous pentoxide (P2O5), Silica gel.
Question 26.
What is Mother liquor ?
Answer:
Mother liquor : In the process of crystalisation, the saturated solution left after separation of crystals is known as Mother liquor.
Question 27.
Define unit of concentration of solution in percentage.
Answer:
Concentration of solution in percentage :
If V ml of the solution contains W g of the solute, percentage of the solution is \(\frac{W}{V}\) × 100%
Question 28.
Define unit of concentration of solution in grams per litre.
Answer:
Concentration of solution in grams per litre :
Its unit is g/L. When 1 litre (1000 ml) of the solution, contains w grams of the solute, its strength is w g/1L.
Broad answer type questions
Question 1.
‘Solubility of A of t°C is y’ — what does it mean ?
Answer:
‘Solubility of A at t°C is y’ — it means y’ g of A can produce a saturated solution when dissolved in a solvent at t°C.
Question 2.
How can you transform a saturated solution into an unsaturated one without adding more solvent ?
Answer:
Without adding more solvent a saturated solution may be made unsaturated by raising its temperature at which the solubility of the solute increases appreciably and the solution thus turns unsaturated.
Question 3.
How does solubility of KNO3, NaCl and CaSO4 change with rise of temperature ?
Answer:
Solubility of KNOt increases rapidly with rise of temperature.
Solubility of NaCl remains almost unchanged with rise of temperature.
Solubility of CaSO4 decreases with increasing temperature.
Question 4.
What is the cause of efflorescence ? Give one example of efflorescent substance.
Answer:
Cause of efflorescence : Efflorescence happens only when the vapour pressure within the hydrated crystal at ordinary temperature is greater than the vapour pressure of the atmosphere. These hydrated crystals are called efflorescent substances.
Example : Na2CO3, 10H2O
Question 5.
What is the cause of deliquescence ? Give one example of deliquescent substance.
Answer:
Cause of deliquescnces : Deliquenscence occurs when the vapour pressure of water in the deliquescent substance is less than the vapour pressure in the atmosphere at ordinary temperature.
Example : CaCl2
Question 6.
Why does effervescence occur when a soda water bottle is opened ?
Answer:
Soda water is a solution of carbon dioxide in water, prepared under high pressure. For this reason when a bottle of soda water is opened, i.e. pressure on the liquid content in the bottle is reduced, effervescence or raising bubbles occur. These effervescences form, as a part of dissolved carbon dioxide gas, escapes through the liquid.
Question 7.
Why edible salt becomes moist in rainy season ?
Answer:
Edible salt (NaCl) becomes moist in rainy season due to the presence of deliquescent substances like MgCl2 and CaCl2 as impurities in it.
Question 8.
How can you prepare a super saturated solution of a solid solute (hypo) at room temperature ?
Answer:
Preparation of a super saturated solution : Super saturated solution can be prepared by heating a few crystals of sodium thiosulphate or hypo (Na2S2O3, 5H2O) in a test tube. The crystals appear to melt or they dissolve in their own water of crystallization and a very concentrated solution of the salt in water is obtained.
The test tube is plugged with cotton wool and allowed to cool to the room temperature. This solution is super saturated and even after cooling, no excess solute separates out. If a crystal of the salt is now added into this solution, the crystal groups in size and the whole liquid begins to solidify with evolution of heat.
Question 9.
Why does clear lime water turn milky when heated ?
Answer:
Clear lime water turns milky when heated : Since solubility of slaked lime [Ca(OH)2] decreases with increase of temperature, clear lime water which is an aqueous solution of Ca(OH)2 or slaked lime turns milky when heated.
Reason : Due to decrease of solubility at a higher temperature, the excess undissolved slaked lime remains in suspension for which the solution appears milky.
Question 10.
Briefly describe the process of crystallisation.
Answer:
Crystallisation : Crystallisation is a process from which crystal of a substance is obtained from its solution. Process of crystallisation for the preparation of crystal :
(a) From saturated solution of a substance : A hot saturated solution of the substance is slowly cooled and then the crystal of that substance is obtained.
(b) From unsaturated solution : An unsaturated solution is vapourised and thus a concentrated solution of it is obtained. Now if this solution is gradually cooled then crystals of the substance are obtained.
(c) Sublimation process : Iodine, camphor etc. are sublimed. If the sublimate so formed is cooled, then the crystals of the substances are deposited in the pot.
(d) From molten matter : Solid sulphur taken in a pot is heated to melt it and then by slowly cooling, the crystals of P-sulphurs are obtained.
Question 11.
What is colloid ? How does it differ from a true and a suspension state ?
Answer:
Colloid : A colloid is a stable heterogenous solution consisting of finely divided particles of a substance (of the size of 10-5 cm to 10-7 cm in diameter) uniformly dispersed in a continuous medium. The component of colloid present in small amount and it behaves like a solute in a solution which is called dispersed phase. The component of colloid present in excess amount and which behaves like a solvent in a solution is called dispersion medium.
Identification of true solution, colloid and suspension : True solution, colloid and suspension are identified on the basis of particle size in it Size of a particle in colloidal state is 10-5 cm to 10-7 cm in diameter. The particle in true solution is 10-8 cm in diameter. The particle in suspension state is
10-8 cm in diameter.
Question 12.
How can an unsaturated solution be converted to saturated state without adding more solute ?
Answer:
(i) Without adding more solute an unsaturated solution may be made saturated by evaporating off a part of the solvent when the remaining lesser quantity of solvent becomes saturated with the initial content of solute.
(ii) Also, by lowering the temperature of the given solution, it may be made saturated since the solute present in the solution may make it saturated at a lower temperature, because solubility of a substance in general decreases with lowering of temperature.
Question 13.
Describe briefly the mechanism of formation of a solution where a solid dissolves in a liquid.
Answer:
Mechanism of formation of solution of a solid in the liquid : When a solid solute comes in contact with a liquid solvent, the tiny solid particles of diameter 10-8 cm or less leave the surface of the solid solute depending on temperature and as concentration of the solution increases, some solid particles return and get deposited on the surface of the lump of solute.
At the initial stage, the rate of leaving the solute surface increases and it slows down when concentration of the solution increases. If the rate of leaving the surface of solute is greater than that of their return, the solid dissolves totally.
Question 14.
Why does the colour of sky appear to be blue ?
Answer:
Colour of sky appears to be blue due to the scattering of blue light by dust particles along with water suspended in air.
Question 15.
What is fire foam ?
Answer:
Fire foam : Carbon dioxide froth made by mixing solution of sodium bicarbonate and alum is called fire foam. It is used in fire extinguishers. A protective colloid such as glue or dextrin is added to stabilise the foam.
Question 16.
Does formation of a solution accompany heat exchange ?
Answer:
There is almost always heat changes accompanying formation of solutions. This means some solutes, when go into solution, heat is evolved and for some other solutes heat is absorbed.
e.g.
Well structured WBBSE Class 9 Physical Science MCQ Questions Chapter 4.3 Solution can serve as a valuable review tool before exams.
Multiple Choice Questions :
Question 1.
Solution is a :
(i) mixture
(ii) element
(iii) compound
(iv) none of these.
Answer:
mixture.
Question 2.
The solvent of sulphur is :
(i) Water
(ii) Ethyl alcohol
(iii) Carbon disulphide
(iv) Benzene
Answer:
Carbon disulphide
Question 3.
If a saturated solution is heated :
(i) the solution becomes unsaturated.
(ii) the solution becomes super saturated.
(iii) the solution remains saturated
Answer:
The solution becomes unsaturated.
Question 4.
If more solvent is added to a saturated solution :
(i) the solution becomes super saturated
(ii) the solution becomes unsaturated
(iii) the solution remains saturated
Answer:
The solution becomes unsaturated.
Question 5.
Solubility decreases with increasing temperature :
(i) KNO3
(ii) CaSO4
(iii) NaCl
(iv) none of these
Answer:
CaSO4
Question 6.
When temperature rises, solubility of gas in liquid:
(i) decreases
(ii) increases
(iii) remains unaltered
(iv) None of these
Answer:
decreases
Question 7.
If the size of the particles are 10-5 cm to 10-7 cm then the solution will be :
(i) true solution
(ii) suspension
(iii) colloid
(iv) none of these
Answer:
colloid
Question 8.
Number of water molecules present in washing soda :
(i) 5
(ii) 6
(iii) 10
(iv) 7
Answer:
10
Question 9.
Deliquescent substance is :
(i) Magnesium chloride
(ii) Washing soda
(iii) Glauber’s salt
(iv) Blue vitriol
Answer:
Magnesium chloride
Question 10.
Fog is :
(i) a solution of liquid in gas
(ii) a solution of gas in gas
(iii) a solution of solid in gas
(iv) a solution of liquid in liquid.
Answer:
a solution of liquid in gas.
Question 11.
Smoke is :
(i) a solution of gas in gas
(ii) a solution of carbon in gas
(iii) a solution of liquid in liquid
(iv) a solution of solid in solid.
Answer:
a solution of Carbon in gas.
Question 12.
Solubility remains almost unchanged with rise of temperature :
(i) NaCl
(ii) CaSO4
(iii) Na2 SO4, 10 H2O
(iv) KNO3
Answer:
NaCl
Question 13.
Phosphorus pentoxide is :
(i) efflorescent substance
(ii) deliquescent substance
(iii) drying agent
Answer:
drying agent
Question 14.
Soluble in chloroform :
(i) sugar
(ii) common salt
(iii) oil
(iv) blue vitriol
Answer:
oil
Question 15.
lodine is soluble in :
(I) water
(ii) aicohol
(iii) acetone
Answer:
alcohol
Question 16.
Unit of concentration of solution is :
(i) g / L
(ii) g / m2
(iii) g / m
(iv) g / cm
Answer:
g / L
Question 17.
Percentage strength is :
(i) 6 g
(ii) 6 kg
(iii) 6%
(iv) 6
Answer:
6%
Question 18.
If excess amount of solute is dissolved in saturated solution then the solution is called :
(i) unsaturated solution
(ii) super saturated solution
(iii) colloid
(iv) emulsion
Answer:
super saturated solution
Question 19.
The ratio of the components of a solution is
(i) fixed
(ii) may vary
(iii) may vary to any extent
(iv) may vary within a limit
Answer:
may vary within a limit.
Question 20.
Aerated cold drinks contain CO2, sugar and water here ; solution is of
(i) Sugar
(ii) CO2
(iii) water
(iv) Sugar and CO2
Answer:
Sugar and CO2
Question 21.
Which one is true solution ?
(i) solution of common salt
(ii) solution of chalk
(iii) milk
(iv) butter
Answer:
Solution of common salt
Question 22.
Particle size of colloid is
(i) 10-8 cm
(ii) 10-4 cm
(iii) 10-3 cm
(iv) 10-5 – 10-7cm
Answer:
10-5 – 10-7cm
Question 23.
Which will not diffuse ?
(i) Suspension
(ii) true solution
(iii) Coloids
(iv) none
Answer:
Suspension
Question 24.
When liquid is dispersed in solid, the product is called :
(i) gel
(ii) sol
(iii) Emulsion
(iv) foam
Answer:
gel
Question 25.
Which of the following in aqueous solution can enter into intermolecular space of water: (i) urea (ii) protein
(iii) DNA
(iv) starch
Answer:
urea
Question 26.
Solubility of which increases with increase of temperature ? :
(i) O2
(ii) NH3
(iii) KNO3
(iv) SO2
Answer:
KNO3
Question 27.
Which of the following solutions is unstable?
(i) Saturated
(ii) Unsaturated
(iii) Super saturated
(iv) Colloidal
Answer:
Super saturated
Question 28.
Which of the following solvents is used to remove nail-polish :
(i) Ethyl alcohol
(ii) Methyl alcohol
(iii) Acctone
(iv) Terpentine oil
Answer:
Acctone
Fill in the blanks :
1. Solute + solvent = _______.
Answer:
Solution
2. A true solution is a ______ mixture.
Answer:
homogeneous
3. The solubility of KNO3 in water ________ tremendously with the rise of temperature.
Answer:
increases
4. A solution is _______ at a temperature if it can dissolve more solute or if its concentration increases.
Answer:
unsaturated
5. A solution of low solute-content is a solution.
Answer:
dilute
6. Solubility of CaSO4 _______ with increasing temperature.
Answer:
decreases
7. A solution is saturated if it does not dissolve any more _______ at a given temperature and if its concentration remains unchanged.
Answer:
solute
8. _____ is a typical state of matter which is intermediate between true solution state and coarse suspension state of matter.
Answer:
Colloid
9. Efflorescent sustances crumble to powder when exposed to ________ due to partial or total loss of water molecules present in their crystalline structures.
Answer:
air
10. Water of crystallisation are some waster molecules which are _______ attached to the molecule of a compound as essential building components of crystals.
Answer:
chemically
11. Solubility of NaCl remains almost _______ with rise of temperature.
Answer:
unchanged
12. Water is a _____ liquid solvent.
Answer:
versatile
13. Soda water contains _______ under pressure.
Answer:
carbon dioxide
14. The particle size (diameter) of colloid lies in between _____.
Answer:
10-5 cm to 10-7 cm.
15. Calcium chloride is a ______ substance.
Answer:
deliquescent
16. Glauber’s salt ( Na2 SO4,10 H2O) is an __________ substance.
Answer:
efflorescent.
17. Crystals are homogeneous solid particles bounded by plane surfaces which meet at sharp edges and have a regular and definite _________ shapes.
Answer:
geometric.
18. Solubility of gas in liquid ________ when temperature rises.
Answer:
decreases
19. Emulsion is a colloid where small particle of one liquid are dispersed in another ________.
Answer:
liquid
20. A solution is a ________ mixture of two or more substances in solid, liquid or gaseous state.
Answer:
homogeneous.
21. Anhydrous copper sulphate is a ________ substance.
Answer:
hygroscopic
22. Unit of concentration of solution is _______.
Answer:
g/L
23. Sodium amalgam is a solution of sodium and _____.
Answer:
mercury
24. A saturated solution can be converted to an unsaturated solution by _____ the solution (Heating/Cooling).
Answer:
heating
25. Solubility of a gas in water increases by ______ pressure.
Answer:
increasing
26. Solubility of a yas at constant pressure may be increased by _______ temperature.
Answer:
decreasing
27. Sodium chloride remains in solution as _____.
Answer:
ions.
28. Rate of crystallization from saturated solution may be increased by ______.
Answer:
seeding
29. Solution is a ______ of a solute in a solvent.
Answer:
homogenous mixture.
30. Colloidal solution contains two components, ____ and ______ .
Answer:
dispersed phase/dispersed medium.
31. Milk is an example of ________ emulsion.
Answer:
oil in water
32. In case of icecream ______ acts as a emulsifier.
Answer:
gelatin
33. Ca(OH)2 shows a ______ of solubility with the _____ of temperature.
Answer:
decrease, increase
34. _____ has no influence an the solubility of a solid ______ in a liqud solvent.
Answer:
Pressure, solute
Well structured WBBSE Class 9 Physical Science MCQ Questions Chapter 2 Force and Motion can serve as a valuable review tool before exams.
Multiple Choice Questions :
Question 1.
Which of the following has no fixed melting point ?
(i) Ice
(ii) Wax
(iii) Lead
(iv) Iron
Answer:
Wax.
Question 2.
The value of acceleration due to gravity :
(i) 980 m/sec
(ii) 9.81 m / sec2
(iii) 9810 m / sec
(iv) 98 m / sec2
Answer:
9.81 m / sec2
Question 3.
If a body is taken in the moon then its weight will be :
(i) increased
(ii) decreased
(iii) same
(iv) zero
Answer:
Decreased.
Question 4.
Soda lime is :
(i) Na2 CO3, 10 H2O
(ii) NaOH
(iii) Mixture of NaOH and CaO
(iv) NaCl
Answer:
Mixture of NaOH and CaO.
Question 5.
Which is most fundamental ?
(i) mass
(ii) weight
(iii) density
Answer:
mass.
Question 6.
What is the ultimate form of all energies ?
(i) Heat
(ii) Light
(iii) Sound
(iv) Chemical
Answer:
Heat.
Question 7.
In an electric cell which type of energy changes to which other ?
(i) Chemical energy to electric energy
(ii) Heat energy to sound energy
(iii) Electric energy to chemical energy
(iv) Chemical energy to sound energy.
Answer:
Chemical energy to electric energy.
Question 8.
When a body is taken to a high altitude from the earth, what changes of mass and weight of the body are observed ?
(i) Mass remains same, weight decreases
(ii) Weight remains same, mass increases
(iii) Both mass and weight increase
(iv) Both mass and weight decrease
Answer:
Mass remains same, weight decreases.
Question 9.
What is the Einstein’s mass energy-equation ?
(i) E = mc2
(ii) E = m2c2
(iii) E = m2c
(iv) E2 = mc2
Answer:
E = m c2.
Question 10.
A non-conventional fuel is :
(i) natural gas
(ii) organic gas
(iii) petroleum gas
(iv) coal
Answer:
Organic gas.
Question 11.
Law of conservation of mass was emunicated by :
(i) Lavoisier
(ii) Dalton
(iii) Proust
(iv) Landolt.
Answer:
Lavoisier.
Question 12.
During photosynthesis, light energy is converted into :
(i) chemical energy
(ii) sound energy
(iii) electric energy
(iv) heat energy
Answer:
Chemical energy.
Question 13.
The force by which a body is attracted towards the centre of the earth is called :
(i) mass
(ii) weight
(iii) density of the body
Answer:
Weight.
Question 14.
Absolute unit of weight in CGS system is :
(i) newton
(ii) dyne
(iii) Joule
Answer:
Dyne.
Question 15.
The ability of doing work is known as :
(i) mass
(ii) weight
(iii) energy
Answer:
Energy.
Question 16.
During nuciear fission, atomic energy is converted into :
(i) heat energy
(ii) electric energy
(iii) magnetic energy
Answer:
Heat energy.
Question 17.
The earth receives solar energy at the rate of about :
(i) 1.8 × 109 megawatt
(ii) 18 × 109 megawatt
(iii) 20 × 109 megawatt
(iv) 2.1 × 109 megawatt
Answer:
18 × 109 megawatt.
Question 18.
In photo-electric cells, light energy is converted into :
(i) sound energy
(ii) magnetic energy
(iii) electrical energy
Answer:
Electrical energy.
Question 19.
The value of acceleration due to gravity at the centre of the earth is :
(i) 0
(ii) less than 0 (zero)
(iii) greater than 0 (zero)
Answer:
0 (zero).
Question 20.
If a body covers equal distances in equal time intervals, then it is :
(i) at rest
(ii) moving with uniform speed
(iii) moving with uniform velocity
(iv) moving with uniform acceleration
Answer:
Moving with uniform speed.
Question 21.
If a body moves with a constant speed, the distance – time graph is
(i) a straight line
(ii) a circle
(iii) a line like a staircase
(iv) a polygon
Answer:
A straight line
Question 22.
The area under the speed-time graph is a :
(i) circle
(ii) parabola
(iii) distance
(iv) none of these
Answer:
distance
Question 23.
The slope of a distance-time graph is :
(i) velocity
(ii) acceleration
(iii) displacement
(iv) speed
Answer:
Speed
Question 24.
The momentum of a body of given mass is proportional to its
(i) volume
(ii) shape
(iii) speed
(iv) density
Answer:
speed
Question 25.
Which of the following has the largest inertia ?
(i) a pin
(ii) your body
(iii) an orange
(iv) a brick
Answer:
your body
Question 26.
A body acted upon by a force must have :
(i) velocity
(ii) displacement
(iii) acceleration
(iv) none of these
Answer:
acceleration
Fill in the blanks :
1. Mass and energy cannot be always considered as ______ quantities.
Answer:
absolute.
2. Einstein showed that in high energy atomic reactions, a small part of ______ of the reactants transforms to energy.
Answer:
mass.
3. After a few changes and transformations, almost all kinds of energy may be proved to originate from the ______.
Answer:
sun.
4. Indian philosophers enunciated that anything that ______ is unperishable.
Answer:
exists.
5. An energy can produce mechanical work directly or after undergoing some ______ transformations.
Answer:
intermediate.
6. Every form of energy ultimately transforms to ______ energy directly or after some intermediate transformations.
Answer:
heat.
7. Energy can neither be created nor destroyed, only one form of ______ energy to other forms.
Answer:
transforms.
8. Electric energy transforms to ______ energy in electric lamps.
Answer:
light.
9. Mass of a body is the quantity of ______ it is made of.
Answer:
matter.
10. Mass is more fundamental than ______
Answer:
weight.
11. Mass of a body is measured by a common balance and ______ of a body is measured with the help of a spring balance.
Answer:
weight.
12. Weight is the ______ that a material body experiences towards the centre of the earth due to the gravitational pull of the earth.
Answer:
force.
13. The weight of a body is ______ in different places of the world.
Answer:
different.
14. Coal, petroleum, natural gas are – sources of energy.
Answer:
non-renewable.
15. If the earth’s gravitational attraction ceases, the acceleration due to gravity also ______
Answer:
ceases.
16. Mass of a body × ______ = Weight of body.
Answer:
Acceleration due to gravity.
17. Energy is defined as ______ to perform work.
Answer:
capacity.
18. Weight of a body is a ______ quantity.
Answer:
vector.
19. Mass is an ______ property of a body.
Answer:
intrinsic.
20. The energy of a moving body possessed by virtue of its ______ is called the kinetic energy.
Answer:
motion.
21. Mass of a body is the ______ of matter it is made of.
Answer:
quantity.
22. To accelerate a body, a must apply ______ on it.
Answer:
force.
23. The SI unit of force is ______.
Answer:
newton
24. A body at rest will remain at ______ it no unbalanced force is applied.
Answer:
rest
25. Action and reaction forces act on ______ bodies.
Answer:
different
26. The force is equal to the product of mass and ______ of the body.
Answer:
acceleration.
Detailed explanations in West Bengal Board Class 9 Physical Science Book Solutions Chapter 4.5 Separation of Mixtures offer valuable context and analysis.
Very short answer type questions
Question 1.
Name a metal and a non-metal which exists in liquid state at room temperature.
Answer:
Mercury is a liquid metal at room temperature.
Bromine is a liquid non-metal at room temperature.
Question 2.
Name a non-mental heavier than water.
Answer:
Iodine is a non-metal heavier than water
Question 3.
What type of change occurs when milk is converted to curd ?
Answer:
Chemical change occurs when milk is converted to curd.
Question 4.
What type of change occurs when quick lime is treated with water ?
Answer:
Chemical change occurs when quick lime is treated with water.
Question 5.
Name a non-metal having lustre.
Answer:
Iodine is a non-metal having lustre.
Question 6.
Name a metal lighter than water.
Answer:
Lithium is a metal lighter than water.
Question 7.
Mention chemical reaction which is influenced by pressure.
Answer:
In crackers, a mixture of potassium chlorate and sulphur explodes under pressure.
Question 8.
Mention chemical reaction which is influenced by contact.
Answer:
Quick lime in contact with water produces slaked lime with evolution of heat.
Question 9.
Which gas has the smell of rotten egg ?
Answer:
Hydrogen sulphide (H2S) gas has the smell of rotten egg.
Question 10.
Mention a chemical reaction that is influenced by a catalyst.
Answer:
When a mixture of MnO2 and KClO3 are heated, oxygen gas is evolved. In this reaction MnO2 acts as a catalyst.
Question 11.
Name two solids which may be identified by colour.
Answer:
The colour of blue vitriol or hydrated copper sulphate is blue. The colour of chalk powder is white.
Question 12.
Mention a chemical reaction where heat is absorbed.
Answer:
Quick lime in contact with water produces slaked lime with evolution of heat.
Question 13.
Name a non-mental that conducts electricity.
Answer:
Graphite or Gas carbon, a non-metal conducts electricity.
Question 14.
Name two metalloids.
Answer:
Arsenic (As) and Antimony (Sb) are two metalloids.
Question 15.
Sugar is added to
(i) concentrated sulphuric acid and
(ii) water. State whether a physical change occurs or a chemical change during these two incidents.
Answer:
(i) Chemical change occurs when sugar is added to concentrated sulphuric acid.
(ii) Physical change occurs when sugar is added to water.
Question 16.
Name an electropositive metal and an electropositive non-metal.
Answer:
Sodium is an electropositive metal.
Hydrogen is an electropositive non-metal.
Question 17.
Cite one physical change where heat is absorbed.
Answer:
When ammonium chloride or ammonium nitrate is dissolved in water heat is absorbed.
Question 18.
Name a soft metal.
Answer:
Sodium (Na) is a soft metal.
Question 19.
Give an example where physical and chemical changes take place simultaneously.
Answer:
Burning of candle is an example of simultaneous occurrence of both physical and chemical change.
Question 20.
Give an example of a slow reaction.
Answer:
Rusting of iron is an example of a slow reaction.
Question 21.
State one chemical change where heat is absorbed.
Answer:
Heat is absorbed when nitrogen and oxygen combine to form nitric oxide.
Question 22.
Give an example of a metal which reacts both with acid and alkali.
Answer:
Zinc is the metal which reacts both with acid and alkali.
Question 23.
Which type of ion is formed by hydrogen in NaH ?
Answer:
H(-) ion is formed by hydrogen in NaH.
Question 24.
Give an example of natural physical change.
Answer:
Melting of glacier is an example of natural physical change.
Question 25.
Give an example of a natural chemical change.
Answer:
Forest fire is an example of natural chemical change.
Short Answer Type Question
Question 1.
Define properties of matter ?
Answer:
Properties of matter : Each and every substance has its special characteristics by which we can identify it. These characteristics of matter are known as the properties of matter.
Question 2.
What do you mean by physical properties of matter ?
Answer:
Physical properties of matter : Physical properties of matter are those which are observed externally and can be determined without changing the composition of matter.
Question 3.
What are the different forms of matter ?
Answer:
Matters can exist normally in three forms.
These forms are :
Question 4.
Define melting point of a solid.
Answer:
Melting point of a solid: Melting point of a solid is the temperature at which the solid begins to transform to liquid under normal pressure, the temperature remains constant till the whole mass of the solid converts to liquid.
Question 5.
Define boiling point of a liquid.
Answer:
Boiling point of a liquid: Boiling point of a liquid is the temperature at which the liquid begins to transform rapidly to its vapour state under normal atmospheric pressure and the temperature remains constant until whole mass of the liquid converts to its vapour.
Question 6.
What do you mean by chemical properties of matter ?
Answer:
Chemical properties of matter: Chemical properties of matter are those which are manifested when the matter undergoes chemical changes involving the change of its composition.
Question 7.
What do you mean by physical change ?
Answer:
Physical change : The physical change is a temporary change in which internal structure of the molecules of the component remains unchanged, only physical state of matter is changed.
Question 8.
What do you mean by chemical change ?
Answer:
Chemical change : A chemical change is a permanent change in which the substance gives rise to one or more new substances with different compositions and properties.
Question 9.
Which of the following are physical changes and which are chemical changes ? Give one reason for each answer.
(i) Lime is treated with water
(ii) Water is boiled to steam
(iii) Rice is converted to puffed rice
(iv) Sugar is dissolved in water
(v) Iron is magnetised
(vi) Souring of milk
(vii) Coal is burnt in air
(viii) A platinum wire is heated
(ix) Rusting of iron
(x) Burning of magnesium wire
(xi) Melting of ice
(xi) Burning of candle.
Answer:
(i) Lime is treated with water: This is a chemical change.
When quick lime is added to water, it boils and ultimately slaked lime is formed. It is heavier than quick lime having different properties also. So it is a chemical change.
CaO + H2O → Ca (OH)2 + heat
(ii) Water is boiled to steam: This is a physical change.
After some time steam returns to water, so it is a temporary change.
(iii) Rice is converted to puffed rice: This is a chemical change. Puffed rice cannot be converted to rice again, so it is a permanent change.
(iv) Sugar is dissolved in water: This is a physical change. A lump of sugar breaks into tiny pieces while it dissolves in water. If the solution is now heated to boil off water, sugar is again obtained. So it is a temporary change.
(v) Iron is magnetised: This is a physical change. An iron bar acquires magnetism when it is rubbed with a magnet several times. There has been only a rearrangement of its molecules. The new property acquired by the iron is temporary because when it is heated strongly, its magnetic property is removed.
(vi) Souring of milk: Souring of milk is a chemical change. In this process, milk is converted to curd which is sour in taste. The sour taste is due to the conversion of fat molecules of milk to sour lactic acid. Curd thus produced cannot be converted back to milk.
(vii) Coal is burnt in air: Burning of coal in air is a chemical change. When coal is burnt in air, carbon dioxide gas and some ashes produce from which the original substance cannot be recovered. So it is a permanent change.
(viii) A platinum wive is heated: This is a physical change. When platinum wire is heated it burns becoming white hot and radiates light but there is no change in the composition of the matter. It regains its initial state on cooling.
(ix) Rusting of iron: This is a chemical change. Rusting is nothing but hydrated ferric oxide which is formed by the reaction of iron, oxygen and water. It is heavier than iron. Iron and rusting of iron are different in composition. So, it is a permanent change.
(x) Burning of magnesium wire : This is a chemical change.
When magnesium burns in air or oxygen, magnesium oxide is produced.
2Mg + O2 = 2MgO.
When magnesium is burnt in air, Mg3 N2 also produces. Magnesium cannot be recovered from these new substances. So, this is a permanent change.
(xi) Melting of ice: This is a physical change. No new substance produces during this change. Water can be cooled back to ice. So, this is a temporary change.
(xii) Burning of Candle: This is a chemical change. New substances like carbon dioxide and water vapour are produced during this change. Original substance cannot be obtained from these new substances. So, this is a permanent change.
Question 10.
Explain one natural physical change.
Answer:
Natural physical change (Melting of Glacier): Ice exists in the peak of a mountain but in summer it flows down as water in the plane surface or earth. Glacier, a slowly moving mass of ice is transformed into water when pressure, temperature and other geographical conditions change.
Water thus produced is ultimately mixed with sea. In summer, water from river, sea and other sources are again transformed to vapour and is condensed to ice in peak of mountain in cold. So melting of glacier is a temporary change. So, melting of glacier is an example of natural physical change.
Question 11.
Explain one natural chemical change.
Answer:
Natural chemical change (Forest fire) : Far from seaside, in summer or any hot condition fire is formed in the forest due to friction of woods. The fire spreads quickly in the forest. As a result the trees and the bushes burn forming carbon dioxide and the wood charcoal with some other organic materials. So, forest fire is a permanent change.For this reason, forest fire is considered as natural chemical change.
Question 12.
Physical and chemical changes take place simultaneously when a candle burns — Explain.
Answer:
Simultaneous occurrence of physical and chemical change: When a candle burns in air, a portion of it melts. The molten part when cooled returns to solid wax, the material of candle. So this part is a physical change.
Major part of the candle converts into water vapour and carbon dioxide gas. Original portion of the candle cannot be obtained from these water vapour and carbon dioxide. So this is a chemical change.
So, in this case, physical and chemical changes occur at the same time.
Question 13.
Give an example where physical and chemical changes take place simultaneously.
Answer:
When water is sprayed over quick lime, and much heat generates and quick lime converts to slaked lime. The produced heat converts a part of water to steam which is a physical change since steam may be cooled to water again.
The conversion of quick lime to slaked lime is a chemical change as the slaked lime thus formed cannot be converted to its original form (quick lime) easily. So, both the physical and chemical changes occur simultaneously.
Question 14.
Give the example of a slow reaction.
Answer:
Slow reaction: The reaction in which the amount of activation energy is high, is called slow reaction.
Example : Organic compounds or some of the covalent compounds undergo chemical reactions slowly.
Question 15.
Give the example of a fast reaction.
Answer:
Fast reaction : The reaction in which the amount of activation energy is low, called fast reaction at given temperature. The time required for the completion of such reactions is about 10-14 to 10-15 second.
Example : Ionic compounds which are inorganic in nature normally undergo fast reaction.
Question 16.
What do you mean by catalyst and catalysis?
Answer:
Catalyst and catalysis : A catalyst is a substance that alters the rate of a chemical reaction without itself being used up and can be recovered unchanged chemically at the end of a chemical reaction. The phenomenon of acceleration or retardation of chemical reactions by the presence of a catalyst is called catalysis.
Question 17.
Explain positive catalyst with example.
Answer:
Positive catalyst: Catalyst which can accelerate the rate of chemical reaction is called positive catalyst.
Example:
Question 18.
Explain negative catalyst with example.
Answer:
Negative catalyst: Catalyst which can retard the rate of the themical reaction is called negative catalyst.
(ii) Antifreezes like glycerol which retard the rusting of the machines.
Question 19.
What do you mean by exothermic change?
Answer:
Exothermic change: Exothermic change is one in which a substance undergoing a physical change or a chemical change releases heat into its surroundings.
Examples :
(j) Exothermic physical changes: When caustic soda (NaOH) dissolves in water or when concentrated sulphuric acid (H2SO4) is mixed in water, plenty of heat evolves in each of the physical change 8.
(ii) Exothermic chemical changes:
Question 20.
What do you mean by endothermic change?
Answer:
Endothermic change: Endothermic change is one where a substance undergoing physical or chemical change takes heat from its surroundings.
Examples :
(i) Endothermic physical changes : In the dissolution process of ammonium chloride (NH4Cl) or ammonium nitrate (NH4NO3) in water, heat is absorbed.
(ii) Endothermic chemical changes:
Question 21.
What is fractional distillation?
Answer:
Fractional distillation : The process by which two or more miscible liquids are separated by distillation using the difference in their boiling point is known as fractional distillation. When the boiling points of two or more miscible liquids differ by about 15°C — 20°C, these are separated by simple fractional distillation.
Question 22.
How two immiscible liquids are separated?
Answer:
Separation of two immiscible liquids: When two different liquids do not mutually dissolve in each other but remain floating one above the other, it is called a mixture of two immiscible liquids. They are separated with the help of a separating funnel.
Question 23.
What is chromatography?
Answer:
Chromatography : It is a modern technique by which mixture of different substances are separated. In this method due to difference in adsorption of different substances in solid phase (adsorbent) and the difference in migration of the substances in the mobile phase (liquid or gas) various substances are separated.
Question 24.
What do you mean by paper chromatograpny?
Answer:
Paper chromutographv : This is a very easy technique to separate the various organic dyes present in the writing ink or printing ink.
Question 25.
What are the advantages of chromatography?
Answer:
Advantage of chromatography :
Question 26.
What do you mean by sublimation?
Answer:
Sublimation: There are some solids which on heating directly transform into vapour phase without transforming through the intermediate liquid state. This phenomenon is known as sublimation. Using this method two different solids ammonium chloride (NH4Cl) and sand (SiO9) can be separated.
Question 27.
What are metals?
Answer:
The elements having lustre, normally solid and heavy, which conduct heat and electricity, electro-positive in nature producing metallic sound on striking are called metals.
Example : Fe, Al, Zn, Na, Ag etc.
Question 28.
What do you mean by non-metals
Answer:
Non -Metals: The elements which do not possess any lustre, normally exist in liquid and gaseous state, poor conducting ability of heat and electricity, electronegative in character are called non metals.
Example : H2, O2, Cl2, N2, C, S, P etc.
Question 29.
What is a metalioid ?
Answer:
Metalloids : The elements which have both metallic and non metallic characters are known as metafloids. Arsenic (As), antimony (Sb).
Question 30.
What are reasons for separting the components of mixture?
Answer:
The components of a mixture are separated because of the following reasons :
Question 31.
What is distillation?
Answer:
Distillation: The process of converting a liquid into its vapour by heating and the subsequent condensation of the vapour back into the original liquid is known as distillation.
Question 32.
What is separatory funnel?
Answer:
It is an apparatus used for sepating immiscible liquids. The liquids do not mix with each others and due to the difference in densities, the liquids remain in separate layers in the sepratory funnel.
Broad answer type questions
Question 1.
Give an example for each of the chemicaì changes influenced by
(a) Contact
(b) Heat
(c) Pressure
(d) Light
Answer:
(a) Contact: Quick lime (CaO) in contact with water produces slaked lime [Ca(OH)2] with generation of heat.
(b) Heat: When mercury is heated in air, red mercuric oxide is formed.”
2Hg + O2 = 2HgO (red)
(c) In Haber’s process nitrogen combines with hydrogen at 200 atmospheric pressure forming ammonia.
(d) Light induces and regulates the chemical reactions involved in photography.
Question 2.
Explain with examples how matter is identified with the help of physical properties.
Answer:
Matters are identified by physical properties :
(a) Physical State: At ordinary conditions all matters do not exist in the same state.
e.g. at ordinary temperature, gold, silver, iron all are solid.
Water, milk, oil are liquid.
Hydrogen, oxygen, carbon dioxide etc. are gaseous.
(ii) Touch: Many substances may be identified by touching.
e.g. Slippery nature of graphite is easily distinguished with the coarse nature of chalk.
(iii) Smell : Different substances have different smell.
e.g. Ammonia gas has pungent smell, hydrogen suiphide has the distinctive smell of rotten egg and oxygen gas is odourless.
(iv) Colour : Some substances have distinctive colours which help us to identity them.
e.g. Blue vitriol (hydrated copper sulphate) has blue colour while gold has a bright yellow colour.
(v) Solubility : Different substances have different solubilities in different solvents.
e.g. Sugar is soluble in water but not in petrol. On the other hand sulphur is not soluble in water but soluble in carbon disuiphide.
(vi) Magnetic property : Different substances may be distinguished with their different magnetic properties.
e.g. Iron, cobalt, nickel and some of their alloys may be magnetised or attracted by a magnet while gold, copper etc. have no such property.
(vii) Melting point and boiling point: Different crystalline solids have different melting points and they are identified by their melting points or freezing point. Again different pure liquids have different boiling point and they are identified by their boiling point.
e.g. At 1 atm. pure ice has melting point 0°C while pure water has boiling point 100°C.
Question 3.
Explain with examples how matter is identified with the help of chemical properties.
Answer:
Matters are identified by chemical properties:
(i) Action of heat:
But sugar when treated with water, it simply dissolves without producing any chemical change.
(iii) Action with acid:
Zn (Zinc) + (dilute) H2SO4 → ZnSO4 + H2 ↑
But the same acid in ordinary condition has no action on copper.
(iv) Action with alkalis:
NH4Cl + NaOH → NaCl + NH3 ↑ + H2O
But sodium chloride does not react with alkali.
Question 4.
Compare between physical change and chemical change.
Answer:
Difference between physical and chemical change:
Question 5.
What are the characteristics of catalyst?
Answer:
Characteristics of catalyst :
Question 6.
Describe how two miscible liquids may be seperated by fractional distillation.
Answer:
Separation of two miscible liquids by fractional distillation:
When the boiling points of two or more miscible liquids differ by about 15°C — 20°C, these are separated by simple fractional distillation.
Procedure: The liquid mixture is kept in a distilation flask fitted with a Leibig’s condenser. The other end of the condenser is connected with a receiving flask for collection of the distillate. Now the liquid mixture is heated. The volatile liquid i.e. liquid having lower boiling point through the condenser in the form of vapour.
The vapour is condensed to liquid and collected in a receiver. Liquid having higher boiling point is left in the distillation flask. By controlling rate of heating and temperature of the fractionating column, a good separation of the components is possible.
Question 7.
Discuss the method of separation of two immiscible liquids by separating funnel.
Answer:
Separation of two immiscible liquids by separating funnel:
A mixture of two immiscible liquids are easily separated by using separating funnel. Each liquid forms its own liquid layer due to difference in density.
Procedure: Two immiscible liquids are kept in a separating funnel and are shaken for few minutes keeping the stop-cock closed. The liquid mixture is allowed to stand for half an hour. The immiscible liquids separate into two distinct layer.
The liquid with lower density remains in the upper layer and the liquid with higher density will be deposited in the lower layer. The denser liquid in the lower layer can be easily run out by opening the stop-cock lying in the bottom of the funnel and collected in a conical flask. Later, the liquid in the upper layer may be collected in another flask.
Question 8.
Briefly describe how the colouring matters of ink can be separated by paper chromatoqraphy.
Answer:
Separation of colouring matters of ink by paper chromatography:
Paper chromatography: It is a very easy technique to separate the colouring matters present in the ink.
Materials required :
Procedure :
Question 9.
How will you separate ammonium chloride and sand by the method of sublimation?
Answer:
Separation of ammonium chloride and sand by the method of sublimation:
Procedure :
Question 10.
State three basic characteristics of metal and non-metal with respect to
(a) ion formation
b) reaction with oxygen
(c) conduction of electricity and heat.
Answer:
(a) Ion formation : Metals form positive ions by loss of electron.
e.g. Na – e → Na+ ; Mg – 2e → Mg2+ ; Al – 3e → Al3+
Non-metals form negative ions by gaining electron.
e.g. Cl + e → Cl– ; O + 2e → O2- ; N + 3e → N3-
(b) Reaction with oxygen : Almost all metals (except Ag, Au) react with oxygen to produce metallic oxides; aqueous solution of some of these like Na2O, K2O are alkali.
Na + O2 → Na2O; Na2O + H2O = 2 NaOH
K + O2 → K2O ; K2O + H2O = 2 KOH
Oxides of non-metals are usually acidic in nature. Aqueous solution of oxides of C, S, P etc. are acidic.
C + O2 → CO2 ; CO2 + H2O = H2CO3 (Carbonic acid)
S + O2 → SO2 ; SO2 + H2O = H2SO3 (Sulphurous acid)
(c) Conduction of electricity : Metals are good conductors of heat and electricity.
Non-metals are usually bad conductors of heat and electricity.
Exception: Graphite, though a non-metal is a good conductor of heat and electricity.
Well structured WBBSE Class 9 Physical Science MCQ Questions Chapter 1 Measurement can serve as a valuable review tool before exams.
Multiple Choice Questions :
Question 1.
What is the SI unit of temperature ?
(i) calorie
(ii) kelvin
(iii) centrigrade
Answer:
Kelvin.
Question 2.
Which unit should be chosen to measure the distance between two stars ?
(i) kilometre
(ii) femtometre
(iii) light year
Answer:
light year.
Question 3.
Which physical quantity has the dimension [MLT-2] ?
(i) velocity
(ii) acceleration
(iii) temperature
Answer:
acceleration.
Question 4.
What is the unit of atomic weight ?
(i) gram
(ii) milligram
(iii) no unit
Answer:
no unit.
Question 5.
At what temperature density of water is maximum ?
(i) 0°C
(ii) 4°C
(iii) 1 K
Answer:
4°C.
Question 6.
Of the following quantities, which is scaiar quantity ?
(i) velocity
(ii) time
(iii) weight
(iv) force
Answer:
time.
Question 7.
The dimension of velocity is :
(i) [LT-1]
(ii) [M L T-2]
(iii) [M L-1 L-2]
(iv) [M L T-1]
Answer:
[LT-1].
Question 8.
Which one is not fundamental unit ?
(i) metre
(ii) litre
(iii) kilogram
(iv) second
Answer:
litre.
Question 9.
Light year is the unit of :
(i) time
(ii) distance
(iii) temperature
Answer:
distance.
Question 10.
To measure the diameter of an atom, the unit is used :
(i) ohm
(ii) metre
(iii) fermi
(iv) millilitre
Answer:
fermi.
Question 11.
1 fermi is :
(i) 10-15 metre
(ii) 10-10 metre
(iii) 10-5 metre.
Answer:
10-15 metre.
Question 12.
1 X-unit is :
(i) 10-13 cm
(ii) 10-12 cm
(iii) 10-11 cm
Answer:
10-11 cm.
Question 13.
1 light year is :
(i) 9.45 × 1010 km
(ii) 9.47 × 1011 km
(iii) 9.467 × 1012 km.
Answer:
9.467 × 1012 km.
Question 14.
Which one is scalar quantity :
(i) acceleration
(ii) velocity
(iii) work
Answer:
work.
Question 15.
An object has density 4 g c .c. and volume 20 c.c.. What will be the mass of the object ?
(i) 80 g
(ii) 40 g
(iii) 5 g.
Answer:
80 g.
Question 16.
Identify the vector quantity :
(i) mass
(ii) volume
(iii) time
(iv) weight
Answer:
Weight.
Question 17.
The unit of volume is :
(i) fundamental unit
(ii) derived unit
(iii) none of these
Answer:
derived unit.
Question 18.
The density of Hg is :
(i) 13.6 g c. c.
(ii) 12.6 g c. c.
(iii) 11.6 g c. c.
Answer:
13.6 g c. c.
Question 19.
The watch used in run competition is :
(i) pendulum clock
(ii) stopwatch
(iii) table clock
Answer:
stopwatch.
Question 20.
The dimension of Retardation is :
(i) [LT-1]
(ii) [LT-2]
(iii) [LT]
Answer:
[LT-2]
Question 21.
1 per sec is :
(i) 30.84 km
(ii) 29.75 km
(iii) 28.82 km
Answer:
30.84 km
Question 22.
1 Astronomical unit (Au) is :
(i) 1.495 × 108 km
(ii) 2.57 km
(iii) 3.82 km
Answer:
1.495 × 108 km .
Question 23.
The dimensions of force are :
(i) [M2 L T-2]
(ii) [M L-2 T-2]
(iii) [M L T2]
(iv) [MLT-2]
Answer:
[MLT-2]
Question 24.
The prefix mega stands for
(i) 10-9
(ii) 108
(iii) 107
(iv) 106
Answer:
106
Question 25.
The periodic time of a simple pendulum is propartional to
(i) its lengths
(ii) square root of its length
(iii) reciprocal of its length
(iv) square of its length
Answer: Square root of its length.
Question 26.
One litre stands for :
(i) 103 m3
(ii) 10-3 m3
(iii) 10 m3
(iv) 100 m3
Answer:
10-3 m3
Fill in the blanks
1. A scalar physical quantity can be expressed with its magnitude but _________ any direction.
Answer:
without.
2. _________ physical quantities are those, each of which associates one or more fundamental physical quantities.
Answer:
Derived.
3. A vector physical quantity is expressed with magnitude, proper unit as well as a _________.
Answer:
direction.
4. Physical quantities are of two types, _________ and vector.
Answer:
scalar.
5. Any __________ quantity related to a material body or any natural or mechanical event is known as a physical quantity.
Answer:
measurable.
6. The time that elapses between two consecutive apparent transits of the Sun across the __________ at a place is known as Solar day.
Answer:
meridian.
7. Dimension is a _________ or quotient of the fundamental quantities involved in a derived physical quantity raised to appropriate powers.
Answer:
product.
8. Some physical quantities have no units, since each is expressed by a _________ of similiar physical quantities.
Answer:
ratio.
9. Derived units are obtained by using a fundamental unit more than once or by using two or more __________ units.
Answer:
fundamental.
10. Measurement of a physical quantity means to compare it with a standard physical quantity of the _________ nature accepted by all in the world.
Answer:
same.
11. Spring balance measures the __________ of a body.
Answer:
weight.
12. __________ is the mass per unit volume.
Answer:
Density.
13. Velocity is a _________ quantity.
Answer:
vector.
14. Anything that can be measured is a _________ quantity.
Answer:
physical.
15. CGS system is also known as ___________ system.
Answer:
metric.
16. InCGS system unit of mass is __________.
Answer:
gram.
17. InCGS system, unit of density is ___________.
Answer:
g/c.c.
18. Mass of 1 c.c. of pure water at 4°C is ___________.
Answer:
1 g.
19. A measuring cylinder is used for measuring the volume of a _____________.
Answer:
liquid.
20. The weights in the weight box are in the ratio of ___________.
Answer:
5 : 2 : 2 : 1
21. Work is a ___________ quantity.
Answer:
scalar.
22. 1 A° = ___________ cm.
Answer:
10-8
23. The dimension of force is ____________.
Answer:
[MLT-2]
24. Stopwatch has no __________ hand.
Answer:
hour.
25. The light year is the unit of ____________.
Answer:
distance
26. Small time intervals are measured by ___________.
Answer:
stopwatch.