The mass of a proton is 1.00728 amu and that of a neutron is 1.00867 amu. What is the mass defect (in amu)of a Ni nucleus? (The mass of a nickel-60 nucleus is 59.9308 amu.)

Question

The mass of a proton is 1.00728 amu and that of a neutron is 1.00867 amu. What is the mass defect (in amu)of a  Ni nucleus? (The mass of a nickel-60 nucleus is 59.9308 amu.)

Quizplus · Accepted Answer

The mass of a nickel-60 nucleus is 59.9308 amu. The total mass of 59Ni nucleus will be:
60 * (1.00728 amu) + (60 – 28) * (1.00867 amu) = 59.9317 amu
The mass defect will be:
59.9317 amu – 59.9308 amu = 0.0009 amu
Since the question asks for the mass defect of a single Ni nucleus, we need to divide the answer by the Avogadro’s constant, which is 6.022 x 1023. 
So, the mass defect (in amu) of a single Ni nucleus is:
0.0009 amu / 6.022 x 1023 = 1.496 x 10-27 kg = 0.5491 amu (rounded to four decimal places)

The Mass of a Proton Is 1