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.
(a) (A) is true but (R) is false.
(b) (A) is false but (R) is true.
(c) Both (A) and (R) are true and (R) is the correct explanation of (A).
(d) Both (A) and (R) are true, but (R) is not the correct explanation of (A).
(a) (A) is true but (R) is false.
Explanation –
During the electrolysis of acidified water:
At cathode: 4\mathrm{H^+} + 4\mathrm{e^-} \rightarrow 2\mathrm{H_2}
At anode: 4\mathrm{OH^-} - 4\mathrm{e^-} \rightarrow 2\mathrm{H_2O} + \mathrm{O_2}
The ratio of H2 to O2 liberated is 2:1, so the volume of hydrogen liberated is twice the volume of oxygen formed. Hence, assertion (A) is true.
However, on electrolysis water gives hydrogen and oxygen in the ratio of 2:1 by volume, and not 1:2 as stated. Hence, reason (R) is false.
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