If the energy of a hydrogen atom in `nth` orbit is `E_(n)`, then energy in the nth orbit of a singly ionised helium atom will be

Options

A. `4E_(n)`
B. `E_(n)//4`
C. `2E_(n)`
D. `E_(n)//2`

Answer

A

Explanation

The energy of the electron in the nth orbit is
`E prop Z^(2)*(1)/(n^(2))`
Given `Z_(H)=1,Z_(He)=2`
`therefore (E_(H))/(E_(He))=(Z_(H)^(2))/(Z_(He)^(2))=(1)/(4) implies E_(He)=4E_(H)`
Given, `E_(H)=E_(n)" "therefore E_(He)=4E_(n)`