Give reasons for the following
i. Na, K and Ca metals form hydrides by combination with hydrogen gas, but most other metals do not.
ii. Aluminium easily combines with oxygen but still it can be used for making kitchen utensils.

i. Metals like Na, K and Ca can force the hydrogen atoms to accept electrons given by them and form hydrides.
ii. Aluminium forms a protective oxide layer when it combines with oxygen and hence it is used for making kitchen utensils.