JEE Chemistry 2023 Question with Solution

Given: Four statements about electrochemistry are to be checked for correctness.

Find: The number of correct statements.

A. $E_{cell}$ is an intensive parameter. This statement is correct because an intensive property does not depend on the amount of substance. The value of $E_{cell}$ depends on the nature of the cell, concentration, and temperature, but not on the size of the electrochemical cell.

B. A negative $E^\circ$ means that the redox couple is a stronger reducing agent than the $\text{H}^+/\text{H}_2$ couple. This statement is correct. Since the standard hydrogen electrode has

a redox couple with negative $E^\circ$ has a greater tendency to lose electrons relative to $\text{H}^+/\text{H}_2$ and therefore behaves as a stronger reducing agent.

C. The amount of electricity required for oxidation or reduction depends on the stoichiometry of the electrode reaction. This statement is correct. The required charge depends on the number of electrons involved in the balanced half-reaction, in accordance with Faraday's laws of electrolysis.

D. The amount of chemical reaction that occurs at any electrode during electrolysis by a current is proportional to the quantity of electricity passed through the electrolyte. This statement is correct. This is the direct statement of Faraday's first law of electrolysis.

Therefore, all four statements are correct, so the required number is $4$.

Given: Statements A to D must be tested one by one.

Find: How many statements are correct.

1. For statement A, cell potential $E_{cell}$ is an intensive property, so it does not scale with the amount of material. Hence A is correct.

2. For statement B, a negative standard electrode potential means the couple is less easily reduced than the standard hydrogen electrode and more readily oxidized, so it acts as a stronger reducing agent than $\text{H}^+/\text{H}_2$. Hence B is correct.

3. For statement C, the charge needed for an electrode process depends on electron stoichiometry. More electrons in the half-reaction require more charge. Hence C is correct.

4. For statement D, Faraday's first law states that the extent of chemical change is proportional to the total charge passed through the electrolyte. Hence D is correct.

Thus, the number of correct statements is $4$.