The magnetic behaviour of $\mathrm{Li}_{2} \mathrm{O}$, $\mathrm{Na}_{2} \mathrm{O}_{2}$ and $\mathrm{KO}_{2}$, respectively, are

(D) diamagnetic, diamagnetic and paramagnetic

(A) diamagnetic, paramagnetic and diamagnetic

(B) paramagnetic, paramagnetic and diamagnetic

(C) paramagnetic, diamagnetic and paramagnetic

JEE Main · 2023 · 29 Jan 2023 · Shift 1 · s-Block Elements

The magnetic behaviour of

Li_{2} O

Na_{2} O_{2}

and

KO_{2}

, respectively, are

Answer: (D)

Lithium oxide holds the oxide ion

O^{2 -}

, whose

2 p

shell is complete and fully paired, so it is diamagnetic. Sodium peroxide holds the peroxide ion

O_{2}^{2 -}

, and filling its molecular orbitals leaves every electron paired, so it too is diamagnetic. Potassium superoxide holds the superoxide ion

O_{2}^{-}

, which carries one unpaired electron in a

π^{*}

orbital and is paramagnetic. The three behave as diamagnetic, diamagnetic and paramagnetic respectively.

JEE Main · 2023 · 29 Jan 2023 · Shift 1 · Single correct option