Question

If the surface areas of two nuclei are in the ratio 9 : 49, then the ratio of their mass numbers is

• A. 27 : 343
• B. 9 : 49
• C. 3 : 7
• D. 49 : 81

Hint:

For nuclear physics problems, remember that mass number is proportional to the cube of the linear dimension and surface area is proportional to the square.

Answer 1

The Correct Option is A

The ratio of the mass numbers is proportional to the square of the ratio of surface areas. Therefore, the ratio of mass numbers is given by: $$ \frac{A_1}{A_2} = \left(\frac{S_1}{S_2}\right)^2 = \left(\frac{9}{49}\right)^2 = 27 : 343 $$