Which radioisotope emits alpha particles?

(1) Fe-53 (3) Au-198

(2) Sr-90 (4) Pu-239

The answer is (4) Pu-239. The decay mode of Pu-239 is α decay which means it will emit alpha particles. The other three have the decay mode of β decay.

Answer : Option 4) Pu-239

Explanation : Plutonium-239 is a radioisotope of the element plutonium which emits alpha particles. The decaying process of Pu-239 emits alpha particles. It is widely used as a nuclear reactor fuel. Pu-239 is also used as a primary fissile isotope for the production of nuclear weapons.