Tritium is a radioactive isotope of hydrogen. The nucleus of tritium (sometimes called a triton) contains one proton and two neutrons.
In chemistry, the molar mass  M  is a physical property. It is defined as the mass of a given substance (chemical element or chemical compound) divided by its amount of substance. The base SI unit for molar mass is kg/mol.  The molar mass of a substance is the mass of 1 mol of the substance.