Question

4.24 g of an organic compound on combustion produces 8.45 g of ${CO}_2$ and 3.46 g of water. The mass percentage of $C$ and $H$ in the compound respectively are:

• A. $27.2,18.2$
• B. $54.4,9.1$
• C. $9.1,54.4$
• D. $18.2,27.2$

Answer 1

Answer: (B)

$54.4,9.1$

% of carbon $=\frac{12}{44}\times \frac{Weightof{CO}_2}{Weightoforganiccompound}\times 100$

$=\frac{12}{44}\times \frac{3.45}{4.24}\times 100=54.35\approx 54.4$

% of Hydrogen $=\frac{2}{18}\times \frac{weightof{H}_{2}O}{weightoforganiccompound}\times 100$

$=\frac{2}{18}\times \frac{3.46}{4.24}\times 100=9.06=9.1$

Ans :- $C=54.4$%, $H=9.1$%

Hence, option $B$ is correct.