The number of molecules in 4.25 g of ammonia is:

(a) 1.0 × 10²³

(b) 1.5 × 10²³

(c) 2.0 × 10²³

(d) 3.5 × 10²³

A gas cylinder of capacity of 20 dm³ is filled with gas X the mass of which is 10 g. When the same cylinder is filled with hydrogen gas at the same temperature and pressure the mass of the hydrogen is 2 g, hence the relative molecular mass of the gas is :

1. 5
2. 10
3. 15
4. 20

The empirical formula of the compound is CH₂O, the possible molecular formula can be:

1. C₃H₆O₃

2. C₂H₄O

3. C₄H₃O₂

4. C₄H₆O₂

If relative molecular mass of butane (C₄H₁₀) is 58, then its vapour density will be:

1. 5

2. 29

3. 32

4. 16