question_answer 1)

  Radioactive elements emit a, P and y-rays and are characterised by their half-lives. The radioactive isotope of hydrogen is: (a) protium                         (b) deuterium                   (c) tritium                            (d) hydronium

Answer:

  (c) Tritium is a radioactive isotope. It is P-radioactive and its half-life period is 12.4 years.