Question

Assertion (A): In the electrolysis of acidified water, the volume of hydrogen liberated is twice the volume of oxygen formed.

Reason (R): Water has hydrogen and oxygen in the ratio of 1 : 2 by volume.

विकल्प

• (A) is true but (R) is false.

• (A) is false but (R) is true.

• Both (A) and (R) are true, and (R) is the correct explanation of (A).

• Both (A) and (R) are true, but (R) is not the correct explanation of (A).

Answer 1

(A) is true but (R) is false.

Explanation:

During the electrolysis of water, the decomposition reaction is:

\[\ce{2H2O_{(l)} -> 2H2_{(g)} + O2_{(g)}}\]

According to Gay-Lussac’s Law, the volumes of gases produced are in the same ratio as their coefficients in the balanced equation. Therefore, 2 volumes of hydrogen are produced for every 1 volume of oxygen. This makes the volume of hydrogen exactly twice the volume of oxygen. Therefore, Assertion (A) is true.

The reason states the ratio is 1 : 2 by volume, which is incorrect. As shown in the chemical formula for water (H₂O) and the reaction above, the ratio of hydrogen to oxygen is 2 : 1 by volume. Therefore, Reason (R) is false.