Which of the following statements regarding Drago's rule with respect to $M{\mathrm{H}}_3$ and $M{\mathrm{H}}_2$ (where  belongs to group 15 and group 16 elements respectively except N and O ) are correct?

$\mathrm{s}$-orbital containing lone pair is stereochemically inert.

$s{p}^3$ Hybridisation is not possible in these compounds.

In these compounds. bond angle is  approximately ${90}^{\circ }$.

All of the above