An atom ⁸₃X is bombarded with fundamental particles for 10 seconds. The atom absorbs:

• 10 electrons
• 10 protons
• 9 neutrons

Find the ratio of initial and final surface area of the nucleus.

Solution:

Initial nucleus:

Mass number:

A_i = 8

Electrons do not affect nucleus.

Final mass number:

A_f = 8 + 10 + 9

= 27

Nuclear radius:

R = R₀A^1/3

Surface area:

S = 4πR²

S ∝ A^2/3

Therefore:

S_i : S_f = 8^2/3 : 27^2/3

= 4 : 9

Answer: 4 : 9