What is the energy of a hydrogen atom in the first excited state if the potential energy is taken to be zero in the ground state?

Options

A. 10.2 eV
B. 13.6 eV
C. 23.8 eV
D. 27.2 eV

Answer

C

Explanation

Otherwise `U_1 =- 27.2 eV.` Therefore, we have
increased it by 27.2 eV. It implies that we have
increased it by 27.2 eV in all states.
`U_2 = -6.8 eV`
`:.U_2 = (-6.8+27.2) eV = +20.4 eV`
`E_2 = U_2+K_2 =(20.4 +3.4) eV`
= 23.8 ev.