Question

The Bohr radius of second energy level of $H{e}^{+}$ ion is _________ times the Bohr radius of hydrogen.

Answer 1

Radius of hydrogen like species (one electron atoms) is given by:

$r=0.529\times \frac{n^2}{Z}$

for $H$, $r=0.529$

for $H{e}^{+}$ n=2 and Z=2

$r=0.529\times \frac{2^2}{2}$

$r=0.529\times 2$

Therefore answer is 2.