Which of the following is used to dry ammonia gas?

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

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A)$: Loss of electron from hydrogen atom results in a nucleus of $\sim 1.5 \times 10^{-3} \ pm$ size.
Reason $(R)$: Proton $(H^+)$ always exists in combined form.
In the light of the above statements,choose the most appropriate answer from the options given below:

Hydrogen iodide cannot be prepared by the action of concentrated $H_2SO_4$ on potassium iodide because:

Liquid ammonia is used in refrigeration because of its

Give uses of Dihydrogen as a fuel.