During the change of $\mathrm{O}_{2}$ to $\mathrm{O}_{2}^{-}$, the incoming electron goes to the orbital:

(A) $\pi 2 \mathrm{p}_{\mathrm{y}}$

JEE Main · 2019 · 10 Apr 2019 · Shift 1 · Chemical Bonding and Molecular Structure

During the change of

O_{2}

O_{2}^{-}

, the incoming electron goes to the orbital:

Answer: (B)

From molecular orbital theory,

O X_{2}

ends in

σ 2 p_{z}^{2} π 2 p_{x}^{2} π 2 p_{y}^{2} π^{*} 2 p_{x}^{1} π^{*} 2 p_{y}^{1}

. Adding one electron to make

O X_{2} X^{-}

sends it into one of the singly filled, degenerate antibonding

π^{*}

orbitals, so the extra electron enters the

π^{*} 2 p_{x}

orbital.

JEE Main · 2019 · 10 Apr 2019 · Shift 1 · Single correct option