Online Test of Chapter 3 Atoms and Molecules 3 Science| Class 9th Science

Questions :

1. The percentage of water of crystallisation in CuSO₄.5H₂O is
(a) 36.07
(b) 72.14
(c) 9.02
(d) 56.15

2. Which has the maximum number of atoms?
(a) 108 g of Ag
(b) 56 g of Fe
(c) 27 g of Al
(d) 24 g of 12C

3. 8 g of O₂ has the same number of molecules as
(a) 22 g of CO₂
(b) 7 g of CO
(c) 14 g of CO
(d) 28 g of CO

4. A sample of pure water, irrespective of source, contains 88.89% oxygen and 11.11% hydrogen by mass. The data supports the
(a) Law of conservation of mass
(b) Law of constant composition
(c) Law of multiple proportions
(d) None of these

5. 10 g of CaCO₃ on heating gave 4.4 g of CO₂ and 5.6 g of CaO. The observation is in agreement with the
(a) Law of constant composition
(b) Law of conservation of mass
(c) Law of definite proportion
(d) Law of multiple proportion.

6. The atomic mass of potassium is 39. The number of moles in 78 g of potassium is
(a) 78
(b) 39
(c) 2
(d) 1

7. The mass of sodium in 11.7 g of sodium chloride is
(a) 2.3 g
(b) 4.6 g
(c) 6.9 g
(d) 7.1 g

8. The correct formula of aluminium sulphate is
(a) Al2SO₄
(b) AlSO₄
(c) Al₂(SO₄)₃
(d) Al₃(SO₄)₂

9. The formula unit mass of Na₂SO₄.10H₂O is
(a) 142 u
(b) 322 u
(c) 286 u
(d) 23 u

10. An element A is tetravalent and element B is divalent. The formula of the compound formed by these two elements is
(a) AB₂
(b) A₂B
(c) A₂B₄
(d) AB