The radius of fifth orbit of Li + + is _______ × 10 - 12   m . Take: radius of hydrogen atom = 0 .…

The formula to calculate the radius of Lithium-ion is given by

$R_{\mathrm{Li}}=R_{\mathrm{H}}\times \frac{n^2}{Z} ...\left(1\right)$

Substitute the values of the known parameters into equation (1) to calculate the required radius of the ion.

$\begin{array}{rcl}{R}_{Li}& =& \frac{0.51\times 25}{3}\times {10}^{-10} \mathrm{m}\\ & =& 425\times {10}^{-12} \mathrm{m}\end{array}$