There are in total three isotopes of hydrogen which can be provided as follows:HydrogenDeuteriumTritiumThese are called to be isotopes as they have the same electronic configuration as hydrogen but will contain different molar masses due to the difference in the number of neutrons that are present. For example, hydrogen consists of one electron and there is no presence of neutrons while deuterium consists of the one-electron which is the basic configuration and will contain one neutron as well and tritium will contain one electron and two neutrons in them.