The isotopes of hydrogen are :
(1) Tritium and protium only
(2) Deuterium and tritium only
(3) Protium and deuterum only
(4) Protium, deuterium and tritium
(1) Tritium and protium only
(2) Deuterium and tritium only
(3) Protium and deuterum only
(4) Protium, deuterium and tritium