The stability order of oxide, peroxide and superoxide of (alkali metal is :

Alkali metal's oxide, peroxide, and superoxide have the following stability rankings: normal oxide, peroxide, and super oxide.

$\underset{\text{ Monoxide ion }}{{\mathrm{O}}^{2-}}+\frac{1}{2}{\mathrm{O}}_2\to \underset{\text{ Peroxide ion }}{{\mathrm{O}}_2^{2-}}$

$\underset{\mathrm{peroxide} \mathrm{ion}}{{\mathrm{O}}_2^{2-}}+{\mathrm{O}}_2\to \underset{\text{ Superoxide ion }}{2\left({\mathrm{O}}_2^{-}\right)}$