Question

Given below are two statements labelled as Assertion (A) and Reason (R)

Assertion (A): During electrolysis of aqueous copper sulphate solution using copper electrodes
hydrogen gas is released at the cathode.
Reason (R): The electrode potential of Cu₂⁺ /Cu is greater than that of H⁺/H₂
Select the most appropriate answer from the options given below:
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.

Answer 1

The assertion that hydrogen gas is released at the cathode during electrolysis of aqueous copper sulphate solution with copper electrodes is false, but the reason given is true because copper has a higher electrode potential than hydrogen. The correct answer is option: (d) A is false but R is true.

Step-by-step explanation:

The correct answer to the given question is: (d) A is false but R is true. This is because during the electrolysis of an aqueous copper sulphate solution using copper electrodes, copper is deposited at the cathode, not hydrogen gas. The electrode potential of Cu²⁺/Cu being greater than that of H⁺/H₂ means that the Cu²⁺ ions are more readily reduced than H⁺ ions.

The electrode potential is a measure of the tendency of a chemical species to be reduced, and the more positive the electrode potential, the more likely that species will be reduced rather than something with a less positive (or more negative) potential.

Since copper has a more positive electrode potential than hydrogen, copper ions will be reduced at the cathode, leading to the deposition of copper metal, not the evolution of hydrogen gas.