The energy of a hydrogen atom in the ground state is -13.6 eV. The energy of a He+ ion in the first excited state will be .....

Options

A. `-13.6eV`
B. `-27.2eV`
C. `-54.4eV`
D. `-6.8eV`

Answer

A

Explanation

The energy of a hydrogen like atom in nth orbit is given by
`E_(n)=-Z^(2)xx(13.6)/(n^(2))eV`
For first excited state of `He^(+),n=2,Z=2`
`:. E_(He^(+))=-(4)/(2^(2))xx13.6=-13.6eV`