The hydrated salt, Na₂SO₄.nH₂O, undergoes a 55% loss in mass on heating and becomes anhydrous. The value of n will be:

A metal M forms a compound M₂HPO₄. The formula of the metal sulphate is:

1. M₂SO₄ 

2. MSO₄

3. M(SO₄${)}_2$

4. M₂(SO₄)₃

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

 If 2.74 g of the metal oxide contains 1.53 g of metal, then the empirical formula of vanadium oxide is:

(Atomic Mass of V = 52)

1. ${\mathrm{V}}_2{\mathrm{O}}_3$

2. $\mathrm{VO}$

3. ${\mathrm{V}}_2{\mathrm{O}}_5$

4. ${\mathrm{V}}_2{\mathrm{O}}_7$

A gaseous compound is composed of 85.7% by mass carbon and 14.3% by mass hydrogen. It's density is 2.28 g/litre at 300 K and 1.0 atm pressure. Determine the molecular formula of the compound:

1.  ${\mathrm{C}}_2{\mathrm{H}}_2$

2.  ${\mathrm{C}}_2{\mathrm{H}}_4$

3.  ${\mathrm{C}}_4{\mathrm{H}}_8$

4.  ${\mathrm{C}}_4{\mathrm{H}}_{10}$

On complete combustion, 44 g of a sample of a compound gives 88 g CO₂ and 36 g of H₂O. The molecular formula of the compound may be:

1.  ${\mathrm{C}}_4{\mathrm{H}}_6$ $$

2.  ${\mathrm{C}}_2{\mathrm{H}}_6\mathrm{O}$ $$

3.  ${\mathrm{C}}_2{\mathrm{H}}_4\mathrm{O}$

4.  ${\mathrm{C}}_3{\mathrm{H}}_6\mathrm{O}$

An oxide of iron contains 69.9% iron and 30.1% oxygen by mass. What is its empirical formula?

1. FeO

2. Fe₂O₃

3. Fe₃O₄

4. Fe₃O₂