Question

Assertion :Nitric oxide is paramagnetic while $N_{2}O$ is diamagnetic. Reason: Nitrogen exhibits variable valency in $NO$ and $N_{2}O$.

• A. Both assertion and reason are CORRECT and reason is the CORRECT explanation of the assertion.
• B. Both assertion and reason are CORRECT, but reason is NOT THE CORRECT explanation of the assertion.
• C. Assertion is CORRECT, but reason is INCORRECT.
• D. Assertion is INCORRECT, but reason is CORRECT.

Answer 1

The correct option is D Assertion is INCORRECT, but reason is CORRECT.

The number of electron in nitrogen are 7 and are oxygen 8. Hence number of electrons that would be present in the molecular orbitals in NO are $7+8=15$ . As the number of eletrons are odd, all the electrons in NO molecule can not be paired.Hence a single electron would be present in a $\pi$2p orbitals. Therefore NO is a odd electron species and the gas is hence paramagnetic due to presence of unpaired electrons.
But number of electrons that would be present in the molecular orbitals in NO are $7\ast 2+8=22$ . Therefore, nitrogen exhibits variable valency in NO and $N_{2}O$ and Nitric oxide is para magnetic.
Option D is correct.