The reactivity order of isotope of hydrogen
T>D>H
T<D<H
T=D=H
T<D>H
There are three isotopic forms of hydrogen: Protium (H), Deuterium (D), Tritium (T).The isotopes of hydrogen show similar chemical properties since they possess the same electronic configuration. But they show different physical properties due to different masses. However, the reactivity of protium is more than that of deuterium or tritium. It is due to the relatively stronger D-D or T-T bond.