Question

10ml of gaseous Hydrocarbon on combustion gives 40ml of CO₂ gas and 50ml H₂O (Vapour). The Hydrocarbon is______.

• A. C₄H₅
• B. C₄H₈
• C. C₄H₁₀
• D. C₈H₁₀

Answer 1

The correct option is C

C₄H₁₀

Hydrocarbon on complete combustion gives carbon dioxide(CO₂) gas and Water vapour (H₂O).

The ratio of volumes = 10:40:50 = 1:4:5

All mole of carbon from hydrocarbon is converted into Carbon dioxide.

As 10ml of a hydrocarbon produces 40ml.

So from the ratio of volume Hydrocarbon carbon: Carbon dioxide::1:4

So, 1 mole of hydrocarbon has four moles of carbon.

All the hydrogen from hydrocarbon is converted into water.

As10ml of a hydrocarbon produces 50ml.

Each water molecule has 2 moles of H atoms.

So from the ratio of volume Hydrocarbon carbon: Water::1:10.

So, 1 mole of hydrocarbon has ten moles of Hydrogen.

Thus, option (C) is the correct answer, i.e. Hydrocarbon is ${\mathrm{C}}_4{\mathrm{H}}_{10}$.