What is the shape of a ${\mathrm{H}}_2{\mathrm{O}}_2$ molecule in the gas phase?

Classify the following as covalent, ionic or polymeric interstitial hydride.

${\mathrm{BeH}}_2$

Classify the following as covalent, ionic or polymeric interstitial hydride.

${\mathrm{CaH}}_2$

Classify the following as covalent, ionic or polymeric interstitial hydride.

$\mathrm{RbH}$

Classify the following as covalent, ionic or polymeric interstitial hydride.

${\mathrm{GeH}}_4$

Classify the following as covalent, ionic or polymeric interstitial hydride.

${\mathrm{TiH}}_2$

Complete the following reaction:

$\mathrm{CaO}\left(\mathrm{s}\right) + {\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to$