Question

26 g of an alloy of copper and zinc reacts with $H_{2}S{O}_4$ releasing $4.48lof{H}_2$ at STP. The percentage of zinc in the alloy is:

• A. $10.2$
• B. $76.5$
• C. $25.5$
• D. $48.8$

Answer 1

The correct option is D $48.8$

Reaction of zinc(in alloy) with sulphuric acid can be written as:
$Zn+H_{2}S{O}_4\to ZnS{O}_4+H_2$

Therefore $22.4$ of $H_2$ is produced from = $63.5g$ of $Zn$

$4.48$ of $H_2$ is produced from = $\frac{63.5}{22.4}\times 4.48$ = $12.7g$ of $Zn$

Weight of alloy = $26g$

$\therefore$ %age composition of Zn in alloy = $\frac{12.7}{26}\times 100$ $=48.8$

Hence, option $D$ is correct.