Q 12-12-129JEE MainJEE Main 2025 (2 Apr, Shift 2)Easy
Assuming the validity of Bohr's atomic model for hydrogen-like ions, the radius of the $\text{Li}^{++}$ ion in its ground state is given by $\dfrac{1}{X}a_0$, where $X$ = ______. (Where $a_0$ is the first Bohr radius.)
Answer: (C) $3$
For a hydrogen-like ion $r_n = a_0\dfrac{n^2}{Z}$. For $\text{Li}^{++}$, $Z = 3$, and in the ground state $n = 1$:
$$r = \frac{a_0}{3} \Rightarrow X = 3$$
Solution by Sreeraj P, M.Sc Physics