Ortho and para hydrogen differ in

Oxidation state of hydrogen in compound $X$ is $-1$ and in compound $Y$ is $+1$. $X$ and $Y$ are respectively

Which of the following hydrides is electron-deficient?

Which property of hydrogen distinguishes it from alkali metals?

Metal hydride on treatment with water gives

Given below are two statements,one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A:$ Isotopes of hydrogen have almost same chemical properties,but difference in their rates of reaction.
Reason $R:$ Isotopes of hydrogen have different enthalpy of bond dissociation.
In the light of the above statements,choose the most appropriate answer from the options given below: