Two nuclei have mass numbers 125 and 27, respectively. The mass density ratio of their nuclei will be

1 : 1

The correct answer is Option (4) → 1 : 1

Given:

Mass numbers: $A_1 = 125$, $A_2 = 27$

Radius of nucleus: $R = R_0 A^{1/3}$

Volume of nucleus: $V = \frac{4}{3} \pi R^3 = \frac{4}{3} \pi (R_0 A^{1/3})^3 = \frac{4}{3} \pi R_0^3 A$

Mass of nucleus $\propto A$

Density: $\rho = \frac{\text{mass}}{\text{volume}} \propto \frac{A}{A} = 1$

Answer: Mass density ratio $\rho_1 : \rho_2 = 1 : 1$