The order of filling of molecular orbitals depends on the total number of electrons in the diatomic molecule. There are two general orders:

Order 1 (for molecules with total electrons ≤ 14, e.g., B₂, C₂, N₂):
σ1s, σ*1s, σ2s, σ*2s, π2pₓ = π2pₑ, σ2pₔ, π*2pₓ = π*2pₑ, σ*2pₔ

Order 2 (for molecules with total electrons > 14, e.g., O₂, F₂, Ne₂):
σ1s, σ*1s, σ2s, σ*2s, σ2pₔ, π2pₓ = π2pₑ, π*2pₓ = π*2pₑ, σ*2pₔ

The question asks for the molecule where the σ2pₔ molecular orbital is filled after the π2pₓ and π2pₑ molecular orbitals. This corresponds to Order 1.

Let's analyze the options:

• A) O₂: Total electrons = 8 + 8 = 16. This follows Order 2, where σ2pₔ is filled before π2pₓ and π2pₑ.
• B) Ne₂: Total electrons = 10 + 10 = 20. This follows Order 2, where σ2pₔ is filled before π2pₓ and π2pₑ.
• C) N₂: Total electrons = 7 + 7 = 14. This follows Order 1, where σ2pₔ is filled after π2pₓ and π2pₑ.
• D) F₂: Total electrons = 9 + 9 = 18. This follows Order 2, where σ2pₔ is filled before π2pₓ and π2pₑ.

Therefore, N₂ is the molecule where σ2pₔ is filled after π2pₓ and π2pₑ.

Correct Answer: (C)