Answer:
2H1 and 3H1 are isotopes.
Isotopes
Atoms of the same element having the same atomic numbers, but different mass numbers are termed as isotopes.
Hydrogen is the first element in the periodic table and has the atomic number one. There are three isotopes of hydrogen namely, protium 1H, deuterium 2H or D and lastly tritium 3H or T. The isotopes are different because of the different number of neutrons present in them.
