The bond order and magnetic behaviour of $\mathrm{O}_{2}^{-}$ ion are, respectively:

JEE Main · 2021 · 26 Aug 2021 · Shift 2 · Chemical Bonding and Molecular Structure

The bond order and magnetic behaviour of

O_{2}^{-}

ion are, respectively:

Answer: (D)

The superoxide ion carries

17

electrons, in the configuration

σ_{1 s}^{2} σ_{1 s}^{* 2} σ_{2 s}^{2} σ_{2 s}^{* 2} σ_{2 p_{z}}^{2} π_{2 p_{x}}^{2} π_{2 p_{y}}^{2} π_{2 p_{x}}^{* 2} π_{2 p_{y}}^{* 1}

There are

10

bonding and

7

antibonding electrons, so

bond order = \frac{10 - 7}{2} = 1.5

One electron is left unpaired in the antibonding

π^{*}

set, so the ion is drawn into a magnetic field. The bond order is

1.5

and the ion is paramagnetic.

JEE Main · 2021 · 26 Aug 2021 · Shift 2 · Single correct option