When a nucleus undergoes radioactive decay, its new mass number is?

Question

a. always less than its original mass number.
b. always more than its original mass number.
c. always the same as its original mass number.
d. never less than its original mass number.
e. never more than its original mass number.

Answer 1

(e) never more than the original.

If a beta or gamma decay occurs, the mass number is unchanged - ruling out answers (a) and (b). If alpha decay occurs, the mass number decreases by 4 - ruling out answers (c) and (d).

Answer 2

a. Regardless of the decay alpha, beta or gamma. It's always less...Alpha: it is easy to see, you're losing an helium nucleus...But electrons also have mass so when they are ejected it decreases the mass by a very small amount but it does decrease...Gamma by E=mc^2 says mass is being loss but at an even lower number than a beta emission.

Answer 3

Only (e) is correct.

Answer 4

e is the answer.