Chemistry - Complete s-block Question with Solution | TestHub

(A) True.

Lithium forms mainly $\mathrm{L}{\mathrm{i}}_2\mathrm{O}$ and sodium mainly $\mathrm{N}{\mathrm{a}}_2{\mathrm{O}}_2$.

Potassium, rubidium and caesium mainly form superoxides.

(B) True.

$\mathrm{BeO}$ reacts with both acids and alkalis, so it is amphoteric.

(C) True.

The high melting point of $\mathrm{MgO}$ makes it suitable as a refractory material.

(D) False.

The peroxide ion ${\mathrm{O}}_2^{2-}$ has all electrons paired and is diamagnetic.

The superoxide ion ${\mathrm{O}}_2^{-}$ has one unpaired electron and is paramagnetic.

Therefore, the correct options are A, B and C.