Explain why an atom may go through nuclear decay but another won't? use examples to support your answer.

Nuclear decay or radioactive decay is a process by which the nucleus of an unstable atom loses energy that is in terms of its mass. The radioactivity may cause an atom to lose whichever of its subatomic particles.

The explanation as why some of the atoms go through nuclear decay while others do not its because of the stability of some atoms. Atoms usually tend to follow octet rule, those which do not follow through this may experience the nuclear decay. 

The answer is c. 320 g