WBBSE Class 10 Physical Science MCQ Questions Chapter 3 Chemical Calculations

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