Question

Write the names of isotopes of hydrogen. What is the mass ratio of these isotopes?

Answer 1

Hint: Isotopes are variants of a particular chemical element which differ in neutron number, and consequently in nucleon number. All isotopes of a given element have the same number of protons but different numbers of neutrons in each atom.

Complete step-by-step answer:
With this definition of isotopes in mind, let us now narrow our analysis down to those of Hydrogen.
Hydrogen ($_{1}H$) has three naturally occurring isotopes, sometimes denoted $^{1}H$, $^{2}H$, and $^{3}H$. The first two of these are stable, while $^{3}H$ has a half-life of 12.32 years. There are also heavier isotopes, which are all synthetic and have a half-life less than one zeptosecond (10−21 second).
Hydrogen is the only element whose isotopes have different names in common use today: the $^{2}H$ (or hydrogen-2) isotope is deuterium and the $^{3}H$ (or hydrogen-3) isotope is tritium. The symbols D and T are sometimes used for deuterium and tritium. The IUPAC accepts the D and T symbols, but recommends instead using standard isotopic symbols ($^{2}H$ and $^{3}H$) to avoid confusion in the alphabetic sorting of chemical formulas. The ordinary isotope of hydrogen, with no neutrons, is called protium.
Thus, from the above analysis, we can conclude that the mass ratio of these isotopes is equal to the ratio of their number of nucleons. Therefore, the required mass ratio is 1:2:3.

Note: While there are four more heavier isotopes of Hydrogen, these are insignificant to our analysis both because of their incredibly small half-lives and little to no presence in the environment. These isotopes are heavily radioactive in nature and undergo fission with a matter of a fraction of a few nanoseconds.