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

Which of the following statements are correct?
$(i)$ $NaH_{(s)}$ reacts violently with water to form $NaOH$ and $H_2$
$(ii)$ An example for electron rich hydride is $NH_3$
$(iii)$ Nickel forms saline hydride

Which of the following is radioactive?

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:

Deuterium resembles hydrogen in chemical properties but reacts:

Electrolysis of fused sodium hydride liberates hydrogen at the