question_answer 30)

        The mass of a H-atom is less than the sum of the masses of a proton and electron. Why is this ?

Answer:

                      According to mass energy equivalence established by Einstein, If B represents binding energy of hydrogen atom (= 13-6 ), the equivalent mass of this energy = B/c2. Hence, mass of a H-atom  It is less than sum of the masses of a proton and an electron.