What volume of hydrogen gas at STP would be liberated by action of 50 mL of $\mathrm{H}_{2} \mathrm{SO}_{4}$ of $50 \%$ purity (density $=1.3 \mathrm{~g} \mathrm{~mL}^{-1}$ ) on 20 g of zinc? Given : Molar mass of H, O, S, Zn are 1, 16, 32, 65 $\mathrm{g} \mathrm{mol}^{-1}$ respectively.

JEE Main · 2026 · 05 Apr 2026 · Shift 2 · Some Basic Concepts of Chemistry

What volume of hydrogen gas at STP would be liberated by action of 50 mL of

H_{2} SO_{4}

50%

purity (density

= 1.3 g mL^{- 1}

) on 20 g of zinc?

Given : Molar mass of H, O, S, Zn are 1, 16, 32, 65

g mol^{- 1}

respectively.

Answer: (C)

The mass of pure sulphuric acid taken is

50 \times 1.3 \times \frac{50}{100} = 32.5 g

, i.e.

\frac{32.5}{98} = 0.332 mol

. The zinc supplies

\frac{20}{65} = 0.308 mol

. In

Zn + H_{2} S O_{4} \to ZnS O_{4} + H_{2}

the mole ratio is

1 : 1

, so zinc, being present in fewer moles, is the limiting reagent and

0.308 mol

H_{2}

is liberated. At STP this occupies

0.308 \times 22.4 = 6.892 L

. The volume of hydrogen liberated is

6.892 L

JEE Main · 2026 · 05 Apr 2026 · Shift 2 · Single correct option