The mass number of a nucleus whose radius R is 2.4 fm, will be equal to:

8

The correct answer is Option (2) → 8

Given:

Radius of nucleus: $R = 2.4 \, \text{fm} = 2.4 \times 10^{-15} \, \text{m}$

Radius of nucleus related to mass number $A$:

$R = R_0 A^{1/3}$

Where $R_0 \approx 1.2 \, \text{fm}$

Substitute values:

$2.4 = 1.2 \, A^{1/3} \Rightarrow A^{1/3} = \frac{2.4}{1.2} = 2$

$A = 2^3 = 8$

Answer: Mass number $A = 8$