What do you understand by the term 'non stoichiometric hydrides? Do you expect this type f hydrides to be formed by alkali metals? Justify your answer,

Explanation

Those hydrides which do not have fixed composition are called non-stoichiometric hydrides, and the composition varies with temperature and pressure. This type of hydrides are formed by d and f-block elements. They cannot be formed by alkali metals because alkali metal hydrides form ionic hydrides.