The oxidation number of hydrogen in $MH_2$ is

The reaction in which dihydrogen $(H_2)$ acts as an oxidising agent is:

In the following reaction,assign the state for the underlined atom in the product of complete hydrolysis at $R.T.$:
$\underline{B}_2H_6 + H_2O \longrightarrow H_3BO_3 + H_2 \uparrow$

Hydrogen readily combines with non-metals and thus it shows its

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: Physical properties of isotopes of hydrogen are different.
Reason $R$: Mass difference between isotopes of hydrogen is very large.
In the light of the above statements,choose the correct answer from the options given below:

Tritium is an isotope of