Question

Assertion : $C{r}^{2+}$ is reducing and $M{n}^{3+}$ is oxidising.
Reason : $C{r}^{2+}$ and $M{n}^{3+}$ have $d^4$ configuration.

• A. If both assertion and reason are true and reason is the correct explanation of assertion
• B. If both assertion and reason are true but reason is not the correct explanation of assertion
• C. If assertion is true but reason is false
• D. If both assertion and reason are false

Answer 1

Answer: (B)

$C{r}^{2+}$ is reducing as its configuration changes from $d^4$ to $d^3$ (half-filled $t_{2g}$). The change from $M{n}^{3+}$ to $M{n}^{2+}$ results in the half-filled $d^5$ configurations which has extra stability.