What happens to the atomic mass of two H-2 atoms when they undergo nuclear fusion to form one He-4 atom? Is the mass reduced by .63% of the original mass?

Question

Chemistry question-fusion

Answer 1

H² is deuterium.  Look up the mass of a deuterium atom.  Look up the mass of an He⁴ atom.  Subtract twice the mass of a deuterium atom from the mass of an He⁴ atom, and then find what percent change that is of the mass of 2 deuterium atoms.  That will be your answer.  Hint:  After fusion, the total mass is smaller than the sum of the masses of the components, since some of the mass is converted into binding energy.