Question:
Write the names of isotopes of hydrogen. What is the mass ratio of these isotopes?
Solution:
Hydrogen has three isotopes. They are:
1. Protium, ${ }_{1}^{1} \mathrm{H}$,
2. Deuterium, ${ }_{1}^{2} \mathrm{H}$ or $\mathrm{D}$, and
3. Tritium, ${ }_{1}^{3} \mathrm{H}$ or $\mathrm{T}$
The mass ratio of protium, deuterium and tritium is $1: 2: 3$.