OnlineCBT
Chemistry · PYQ NEET UG 2022
हिन्दीIf radius of second Bohr orbit of the \( \text{He}^+ \) ion is \( 105.8\text{ pm} \), what is the radius of third Bohr orbit of \( \text{Li}^{2+} \) ion?
Correct answer · Option 3
\( 158.7\text{ pm} \)
Explanation
Radius formula is \( r_n = 52.9 \times \frac{n^2}{Z}\text{ pm} \). For \( \text{He}^+ \) (\( n=2, Z=2 \)), \( r_2 = 52.9 \times \frac{4}{2} = 105.8\text{ pm} \). For \( \text{Li}^{2+} \) (\( n=3, Z=3 \)), \( r_3 = 52.9 \times \frac{9}{3} = 158.7\text{ pm} \).
