Question

Assertion :Complex ion $\left[Co\right(N{H}_3{)}_6{]}^{2+}$ is readily oxidized to $\left[Co\right(N{H}_3{)}_6{]}^{3+}$ Reason: Unpaired electron in complex ion $\left[Co\right(N{H}_3{)}_6{]}^{2+}$ is present in 4p orbital.

• 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 C Assertion is correct but Reason is incorrect

The complex ion $\left[Co\right(N{H}_3{)}_6{]}^{2+}$ contain seven electrons in 3d orbitals out of which six are present in $t_{2g}$ level and 1 is present in $e_g$ level.
When on electron is removed from $e_g$ level to obtain $\left[Co\right(N{H}_3{)}_6{]}^{3+}$, the CFSE increases and the stability is achieved.
Hence, the complex ion $\left[Co\right(N{H}_3{)}_6{]}^{2+}$ is readily oxidized to $\left[Co\right(N{H}_3{)}_6{]}^{3+}$
Unpaired electron in complex ion $\left[Co\right(N{H}_3{)}_6{]}^{2+}$ is present in 3d orbital.
Hence the reason is incorrect.