Question

Generally, the value of $E_{M^{3+}/M^{2+}}^0$ of 3d elements ______ across the period.

• A. increases
• B. decrease
• C. remains constant
• D. decrease and then increase

Answer 1

The correct option is A increases

The value of $E_{M^{3+}/M^{2+}}^0$ of 3d elements increase across the period because the third ionisation energy increase across the period. Thus $M^{2+}$ stability increases across the period than $M^{3+}$.. Manganese has high $E_{M^{3+}/M^{2+}}^0$ because $M{n}^{2+}$ is stable due to half filled d-orbital.

+3 oxidation state does not exist for Ni, Cu and Zn


Thus, option (a) is correct.