Question

Which among the following is a colorless paramagnetic gas?

• A. Nitric oxide
• B. Nitrous oxide
• C. Nitrogen oxide
• D. Dinitrogen trioxide

Answer 1

Answer: (A), (C)

Nitrogen oxide

The explanation for the correct option

(A) and (C) Nitric oxide or nitrogen oxide

Paramagnetic nature

• The presence of unpaired electrons in the molecular orbital indicates the compound's paramagnetic nature. The oxide's color is a result of its paramagnetic properties.
• $\mathrm{NO}$ is named nitric oxide or nitrogen oxide. Nitrous oxide is also known as laughing gas or nitrous.
• The molecular orbital configuration of $\mathrm{NO}$ is as follows:-
• $\sigma {\left(1s\right)}^2{\sigma }^{*}{\left(1s\right)}^2\sigma {(2s)}^2{\sigma }^{*}{\left(2s\right)}^2\sigma {\left(2p_z\right)}^2\mathrm{\pi }{\left(2\mathrm{px}\right)}^2\mathrm{\pi }{\left(2{\mathrm{p}}_{\mathrm{y}}\right)}^2\mathrm{\pi }*{\left(2\mathrm{px}\right)}^1$
• One unpaired electron is present. So, it is paramagnetic in nature.
• It is a colorless gas with non-flammable properties.

The explanation for the incorrect option

• Nitrous oxide$\left({\mathrm{N}}_2\mathrm{O}\right)$ is a laughing gas, and it is diamagnetic in nature.
• Dinitrogen trioxide$\left({\mathrm{N}}_2{\mathrm{O}}_3\right)$ is diamagnetic. It is colored.
• Hence, options (B), and (D) are incorrect.

Hence, option (A) is correct. Nitric oxide is a colorless paramagnetic gas.