Two nuclei have mass numbers 27 and 125 respectively. What is the...

The radius of a nucleus is related to its mass number $A$ by the formula $R = R_0 A^{1/3}$.

For the two nuclei with mass numbers $A_1 = 27$ and $A_2 = 125$, the ratio of their radii is:
$\dfrac{R_1}{R_2} = \left(\dfrac{A_1}{A_2}\right)^{1/3} = \left(\dfrac{27}{125}\right)^{1/3} = \dfrac{3}{5}$

Therefore, the ratio of their radii is $3 : 5$.

The nuclear density is approximately constant for all nuclei and is independent of the mass number $A$.

Therefore, the ratio of their nuclear densities is $1 : 1$.

Answer: $3 : 5$ and $1 : 1$