What is heavy water? (Haryana PMT 2010) (a) H O (b) H O

Isotopes are the chemical species that have the same atomic number but a different mass number. Hydrogen has three isotopes namely hydrogen 1 1 H , Deuterium 2 1 D and Tritium 3 1 H . If hydrogen atom of water 2 H O is replaced by deuterium 2 D O , then it is known as heavy water.