Laboratory setup for pure dry hydrogen gas

Steps:

• React iron with hydrochloric acid to generate hydrogen gas via Fe + 2HCl → FeCl2 + H2.
• Pass the moist hydrogen through concentrated sulfuric acid to remove water vapor and ensure dryness.
• Avoid impurities by using a clean setup without additional contaminants.
• Collect the dry gas by downward delivery, as hydrogen is less dense than air.

Why C is correct:

• It sequences iron with hydrochloric acid, followed by water (for dilution), then concentrated sulfuric acid for drying, aligning with the standard gas drying process using H2SO4 as a desiccant.

Why the others are wrong:

• A: Includes water after concentrated sulfuric acid, introducing moisture and preventing dryness.
• B: Retains impurities in the setup, failing to produce a pure sample.
• D: Places concentrated sulfuric acid before water, disrupting the generation and drying sequence.

Final answer: C