nuclear physics

Question 1

Mass defect

Answer 1

mass defect of a nucleus is the difference between the total mass of free individual nucleons and the mass of the nucleus

Question 2

nuclear binding energy

Answer 2

the minimum energy required to separate the nucleons in a nucleus to infinity

Question 3

nuclear fission

Answer 3

the splitting of a single heavy nucleus when bombarded by neutrons to form two or more lighter nuclei of approximately same mass with neutrons emitted

Question 4

nuclear fusion

Answer 4

the combining of two or more light nuclei under very high temperatures to form a single, more massive nucleus

Question 5

radioactivity or radioactive decay

Answer 5

spontaneous and random emission of ionising radiation in the form of alpha particles, beta particles or gamma ray photons from unstable nucleus to become a more stable nucleus

Question 6

spontaneous

Answer 6

because the probability of decay is unaffected by external factors such as temperature, pressure or chemical composition

Question 7

random

Answer 7

because it is impossible to predict if an unstable nucleus will decay at any point in time, all that is known is the probability of decay after a period of time

Question 8

decay constant

Answer 8

the probability per unit time of the decay of a nucleus

Question 9

activity A of a radioactive source

Answer 9

the number of radioactive decays per unit time or rate of radioactive decay in the source

Question 10

half life of a radioactive nuclei

Answer 10

the time taken for the number of undecayed nuclei to be reduced to half its original number