Question

Why Tritium is called radioactive isotope?

Answer 1

See below.

Explanation:

Some isotopes are unstable and in order to become stable they emit either alpha or beta particles. If there is still too much energy left after the emission of particles they emit high energy electromagnetic waves (gamma radiation). In the case of tritium the particles emitted are beta particles and the tritium decays to Helium-3, a non-radioactive isotope of helium.