The sum of protons,electrons and neutrons in the heaviest isotope of hydrogen is

The isotopes of hydrogen are

Which of the following is an incorrect match?

In which of the following reactions is dihydrogen not evolved?

Dihydrogen of high purity $(>99.95 \%)$ is obtained through:

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R).$
Assertion $(A):$ Heavy water is used for the study of reaction mechanism.
Reason $(R):$ The rate of reaction for the cleavage of $O-H$ bond is slower than that of $O-D$ bond.
Choose the most appropriate answer from the options given below: