As per Nuclear Physics there is close relationship between mass number and radius of nucleus. If mass number of A is 216 and mass number of B is 27, then the ratio of nuclear radius \( (r_A/r_B) \) of the two elements is :
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 2 : 1
The nuclear radius grows as the cube root of the mass number, because the nuclear density is the same for all nuclei.
\( \displaystyle R = R_0 A^{1/3} \;\Rightarrow\; \frac{r_A}{r_B} = \left(\frac{A_A}{A_B}\right)^{1/3} \)
\( \displaystyle \frac{r_A}{r_B} = \left(\frac{216}{27}\right)^{1/3} = 8^{1/3} = 2 \)
So \( r_A : r_B = 2 : 1 \).
Note: NTA picked this question from an NCERT (2026-27) exercise and changed the figures. Do not ignore NCERT while practising numericals.
NCERT (2026-27):
Exercises – …
