## In This post you will get answer of Q.

If the energy of a hydrogen atom in nth orbit is $E_n$, then energy in the nth orbit of a singly ionized helium atom will be

Solution:

## The energy of the electron in the nth orbit is

$ E∝ Z^2. frac {1}{n^2} $

Given, $ Z_H=1,Z_{He}=2 $

$ therefore frac {E_H}{E_{He}}= frac {Z_H^2}{Z^2_{He}}= frac {1}{4} $

$ Rightarrow E_{He}=4 E_H $

Given, $ E_H=E_n $

$ therefore E_{He}=4E_n $