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

${\mathrm{TiH}}_2$

Complete the following reaction:

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

Complete the following reaction:

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

Explain. ${\mathrm{H}}_2{\mathrm{O}}_2$ has a higher boiling point than water.

What do you understand by the term hydrogen economy?