The maximum sum of the number of neutrons and protons in an isotope of hydrogen is

The intermolecular force in solid hydrogen is .........

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:

The oxide which is not reduced by hydrogen is

Hydrogen directly combines with

Which of the following statements is correct?