The mass numbers of four elements A, B, C and D are 2, 20, 135 and 235, respectively. Which one of them will be most suitable to make: (i) an atom bomb, and (ii) a hydrogen bomb?

 (i) An atom bomb is based on nuclear fission reactions, so, a heavy nucleus D of mass number 235 is the most suitable to make it.

Explanation

Nuclear fission is the process in which a heavy nucleus splits into two smaller nuclei with the release of a tremendous amount of energy when bombarded with low-energy neutrons.

(ii) A hydrogen bomb is based on nuclear fusion reactions, so, a light element A of mass number 2 is the most suitable to make it.

Explanation

Nuclear fusion is the process in which, when two smaller nuclei are heated to an extremely high temperature under extremely high pressure, they got combined to form a heavy nucleus, and release a tremendous amount of energy.