Question

The energy of hydrogen atom in nth orbit is $E_n$, then the energy in nth orbit of singly ionised helium atom will be

• A. $4E_n$
• B. $\frac{E_n}{4}$
• C. $2E_n$
• D. $\frac{E_n}{2}$

Answer 1

The correct option is A $4E_n$

By using $E=-\frac{13.6Z^2}{n^2}\Rightarrow \frac{E_H}{E_{He}}={\left(\frac{Z_H}{Z_{He}}\right)}^2={\left(\frac{1}{2}\right)}^2\Rightarrow E_{He}=4E_n$