Which one of the following metals forms interstitial hydride easily?

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.

State the abundance and symbol of protium and deuterium in hydrogen atoms.

With which of the following does hydrogen combine directly?

Calcium cyanamide on treatment with steam under pressure gives $NH_3$ and

In context with the industrial preparation of hydrogen from water gas $(CO + H_2)$,which of the following is the correct statement?