Which one of the following molecules is expected to exhibit diamagnetic behaviour? (1) N2 (2) O2 (3) S2 (4) C2

To determine which of the given molecules exhibits diamagnetic behavior, we first need to understand the concepts of paramagnetism and diamagnetism. Diamagnetic substances are those that have all their electrons paired, resulting in no net magnetic moment. In contrast, paramagnetic substances have unpaired electrons, which give rise to a net magnetic moment and cause them to be attracted to magnetic fields.

Analyzing Each Molecule

Let’s examine each of the molecules listed: N2, O2, S2, and C2.

Nitrogen (N2)

Nitrogen has a total of 14 electrons (7 from each nitrogen atom). The molecular orbital configuration for N2 is:

• σ(1s)² σ*(1s)² σ(2s)² σ*(2s)² σ(2p)² π(2p)⁴ π*(2p)⁰

All electrons in N2 are paired, making it diamagnetic.

Oxygen (O2)

Oxygen has 16 electrons. Its molecular orbital configuration is:

• σ(1s)² σ*(1s)² σ(2s)² σ*(2s)² σ(2p)² π(2p)⁴ π*(2p)²

O2 has two unpaired electrons in the π*(2p) orbitals, which makes it paramagnetic.

Sulfur (S2)

Sulfur has 32 electrons. The molecular orbital configuration for S2 is:

• σ(1s)² σ*(1s)² σ(2s)² σ*(2s)² σ(2p)² π(2p)⁴ π*(2p)²

Similar to O2, S2 has unpaired electrons, making it paramagnetic as well.

Carbon (C2)

Carbon has 12 electrons. The molecular orbital configuration for C2 is:

• σ(1s)² σ*(1s)² σ(2s)² σ*(2s)² σ(2p)² π(2p)²

In C2, all electrons are paired, indicating that it is also diamagnetic.

Final Assessment

From our analysis:

• N2: Diamagnetic
• O2: Paramagnetic
• S2: Paramagnetic
• C2: Diamagnetic

Thus, both N2 and C2 are expected to exhibit diamagnetic behavior. However, since the question asks for just one molecule, the answer is: