The empirical formula of an organic compound containing carbon and hydrogen is CH₂. The mass of one litre of this organic gas at STP  is exactly equal to that of one litre of N₂ at STP. Therefore, the molecular formula of the organic gas is:

1. C₂H₄

2. C₃H₆

3. C₆H₁₂

4. C₄H₈

A sample of pure compound is found to have Na = 0.0887 mole, O = 0.132 mole, C = 2.65 × 10²² atoms.

The empirical formula of the compound is 

(1) Na₂CO₃

(2) Na₃O₂C₅

(3) ${\mathrm{Na}}_{0.0887}{0}_{0.132}{\mathrm{C}}_{2.65\times {10}^{22}}$

(4) NaCO

An organic compound containing C, H, and N gave the following on analysis: C = 40%, H = 13.3% and N = 46.67%. Its empirical formula would be:

1. CHN
2. C₂H₂N
3. CH₄N
4. C₂H₇N

An organic substance containing C, H, and O gave the following percentage composition :

C = 40.687%, H = 5.085% and O = 54.228%. The vapour density of this organic substance is 59.

The molecular formula of the compound will be:

1. C₄H₆O₄

2. C₄H₆O₂

3. C₄H₄O₂

4. None of the above

When a solution containing 4.77 gm. of NaCl is added to a solution of 5.77 gm. of AgNO₃, the weight of precipitated AgCl is -

(1) 11.70 gm.

(2) 9.70 gm.

(3) 4.86 gm.

(4) 2.86 gm.

At standard temperature and pressure (STP), the volume of oxygen required to completely combust 30 ml of acetylene under similar conditions is:

1. 100 ml

2. 75 ml

3. 50 ml

4. 25 ml

What is the volume (in litres) of oxygen at STP required for complete combustion of 32 g of CH₄

(1) 44.8

(2) 89.6

(3) 22.4

(4) 179.2

A mixture of gases contains H₂ and O₂ gases in the ratio of 1:4 (w/w). What is the molar

ratio of the two gases in the mixture?

1. 1:4             

2. 4:1             

3. 16:1               

4. 2:1

If the Avogadro number N_A, is changed from 6.022 x 10²³ mol^-1 to 6.022 x 10²⁰ mol^-1 this would change: 

1. The definition of mass in units of grams.

2. The mass of one mole of carbon.

3. The ratio of chemical species to each other in a balanced equation.

4. The ratio of elements to each other in a compound.

20.0 g of a magnesium carbonate sample decomposes on heating to give carbon dioxide

and 8.0 g magnesium oxide. What will be the percentage purity of magnesium carbonate

in the sample? (Atomic weight of Mg = 24)

1. 75

2. 96

3. 60

4. 84