The mass of a proton is 1.00728 amu and that of a neutron is 1.00867 amu. What is the mass defect of a cobalt-60 nucleus? (The mass of a 60Co nucleus is 59.9338 amu.) 4.6136 x 10-23 g 8.9754 x 10-25 g 9.1747 x 10-25 g 1.0993 x 10-25 g 8.0156 x 10-25 g

9.1747x10⁻²⁵g

Explanation:

The mass defect is the difference between the mass of a nucleus and the mass of its particles. The nucleus is formed by protons and neutrons. The atomic number of Cobalt is 27, which means that it has 27 protons in its nucleus. The number of neutrons is the mass (60) less than the number of protons, so it is 33.

Then:

Mass of 27 protons = 27 x 1.00728 = 27.19656 amu

Mass of 33 neutrons = 33 x 1.00867 = 33.28611 amu

Total mass = 60.48267 amu

Mass defect = 60.48267 - 59.9338

Mass defect = 0.54887 amu

1 amu = 1.66054x10⁻²⁴ g, so 0.54887 amu = 9.1747x10⁻²⁵g