Question

When a nucleus with atomic number Z and mass number A undergoes alpha decay, the daughter has the following atomic and mass numbers:

Select one:

a. Z, A

b. Z-2, A-2

c. Z-2, A-4

d. Z-4, A-4

e. Z, A-4

Answer 1

Alpha decay is a type of radioactive decay in which the atomic nucleus emits an alpha particle () and transforms or decays itself into another nucleus. Alpha particle () is nothing but a helium nucleus which have atomic number Z=2 and mass number A=4. Hence, emitting an alpha particle () reduces the atomic number and mass number of the parent nucleus by 2 and 4 respectively.Therefore, the daughter nucleus will have atomic number Z'=Z-2 and mass number A'=A-4. Hence, the correct answer is (c).