Which one of the following properties is generally not applicable to ionic hydrides?

Identify the correct statements from the following:
$i$. Reaction of hydrogen with fluorine occurs even in dark.
$ii$. Manufacture of ammonia by Haber process is an endothermic reaction.
$iii$. $HF$ is an electron-rich hydride.

Number of nucleons in $D_2$ molecule is

Under normal conditions,the hydrogen molecule is not reactive because .........

Which of the following is an example of an interstitial hydride?

Write a note on metallic or non-stoichiometric hydrides.