Which of the given compounds can enhance the efficiency of hydrogen storage tank?

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:

Which of the following cannot be reduced by hydrogen?

Hydrogen does not combine with

Which one of the following methyl diboranes does not exist?

Hydrogen generally forms covalent compounds. Give reason.