Question

$4.5\, g$ of aluminium (at. mass $27\, u$ ) is deposited at cathode from a molten electrolyte containing $Al ^{3+}$ ions by a certain quantity of electric charge. The volume of hydrogen produced at STP from $H ^{+}$ions in a solution by the same quantity of electric charge will be

• A. 44.8 L
• B. 11.2 L
• C. 22.4 L
• D. 5.6 L

Answer 1

Answer: (D)

5.6 L

Answer 2

Equivalent mass of $Al =\frac{27}{3}=9$ Equivalent mass of $H =1$ $\frac{W_{ Al }}{W_{ H _{2}}} =\frac{\text { e mass of } Al }{\text { e mass of } H _{2}}$ $\frac{4.5}{W_{ H _{2}}} =\frac{9}{1}$ $W_{ H _{2}} =0.5\, g$ $\because 2\, g$ of $H _{2}$ at STP occupy volume $=22.4\, L$ $\therefore 0.5\, g$ of $H _{2}$ at STP will occupy volume $=\frac{22.4 \times 0.5}{2}$ $=5.6\, L$