Question

Which of the following two molecular species are Diamagnetic in nature?

• A. \( \text{O}_2 \)
• B. \( \text{N}_2^+ \)
• C. \( \text{C}_2 \)
• D. \( \text{O}_2^{2-} \)

Hint:

Remember, to determine whether a molecule is diamagnetic, check if all electrons are paired in its molecular orbitals. If all electrons are paired, the substance is diamagnetic; if there are unpaired electrons, it is paramagnetic.

Answer 1

The Correct Option is C

Diamagnetic substances do not have any unpaired electrons, meaning that all electrons are paired in their molecular orbitals. Let's analyze the given species:

• \( \text{O}_2 \) has two unpaired electrons in its \( \pi^* \) molecular orbitals, so it is paramagnetic.
• \( \text{N}_2^+ \) also has one unpaired electron in its highest energy molecular orbital, making it paramagnetic.
• \( \text{C}_2 \) is a molecule with a bond order of 2, and both electrons are paired in the molecular orbitals, making it diamagnetic.
• \( \text{O}_2^{2-} \) has all electrons paired, making it diamagnetic.

Thus, \( \text{C}_2 \) and \( \text{O}_2^{2-} \) are diamagnetic, but since the answer asks for a pair, the correct answer is option (C).