Question:medium

Assuming the validity of Bohr's atomic model for hydrogen-like ions, the radius of $ \text{Li}^{2+} $ ion in its ground state is given by $ \frac{1}{X} a_0 $, where $ a_0 $ is the first Bohr's radius.

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For hydrogen-like ions, the radius decreases as the atomic number increases, following the formula \( r = r_0 \frac{n^2}{z} \).
Updated On: Jan 14, 2026
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The Correct Option is C

Solution and Explanation

The radius of a hydrogen-like ion is calculated using the formula:\[r = r_0 \frac{n^2}{z}\]Here, \( r_0 \) represents the radius of hydrogen, \( n \) is the principal quantum number, and \( z \) is the atomic number. For the ion \( \text{Li}^{2+} \), with \( n = 1 \) and \( z = 3 \), the radius is determined as follows:\[r = r_0 \frac{1^2}{3} = \frac{r_0}{3}\]Therefore, \( X = 3 \).
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