Question

Which species does not exhibits paramagnetism:

• A. \(N_2^+\)
• B. \(O_2^-\)
• C. \(CO\)
• D. \(NO\)

Answer 1

The Correct Option is C

To determine which species does not exhibit paramagnetism, we need to understand the concept of paramagnetism and how it relates to electronic configuration.

Paramagnetism: A species is said to be paramagnetic if it has one or more unpaired electrons. Unpaired electrons cause the species to be attracted to a magnetic field.

Let's analyze each species:

1. N_2^+: The molecular nitrogen ion N_2^+ is derived from neutral nitrogen N_2. Neutral N_2 has a total of 14 electrons with no unpaired electrons, but when it loses one electron, N_2^+ has 13 electrons. This results in one unpaired electron in the antibonding π orbital, making it paramagnetic.
2. O_2^-\: Oxygen molecule O_2 naturally has 16 electrons, with two unpaired electrons in its π* orbitals, making it paramagnetic. Removing one electron to form O_2^-\ leaves the molecule with one unpaired electron in the π* orbital, so it remains paramagnetic.
3. CO: Carbon monoxide molecule CO has 14 electrons. The electron filling in molecular orbitals for CO results in no unpaired electrons, making it diamagnetic. Thus, CO does not exhibit paramagnetism.
4. NO: Nitric oxide NO has 15 electrons, which leaves one unpaired electron in its π* orbital, making it paramagnetic.

Conclusion: Among the given species, CO is the only one that is diamagnetic as it does not have any unpaired electrons. Therefore, it does not exhibit paramagnetism.