Question

Assertion :The number of unpaired electrons in the following gaseous ions:
$M{n}^{3+},C{r}^{3+},V^{3+}$ and $T{i}^{3+}$ are 4, 3, 2 and 1 respectively. Reason: Among these Cr${}^{3+}$ is most stable in aqueous solution.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Assertion is incorrect but Reason is correct

Answer 1

The correct option is B Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion

$M{n}^{3+}=[Ar{]}^{18}3d^4,C{r}^{3+}=[Ar{]}^{18}3d^3,V^{2+}=[Ar{]}^{18}3d^2,T{i}^{3+}=[Ar{]}^{18}3d^1$ and Cr${}^{3+}$ is most stable due to greater CFSE of t${}_{2g}^3$ (having a half-filled configuration in t${}_{29}$ level) configuration in aqueous solution.