Question

The ionisation potential of hydrogen atom is -13.6 eV. An electron in the ground state of a hydrogen atom absorbs a photon of energy 12.75 eV. How many diggerent spectral lines can one expect when the electron make a downward transition
A. 1
B. 4
C. 2
D. 6

Answer 1

Correct Answer - D
`E=E_(1)//n^(2)`
Energy used for excitation is 12.75 eV
I.e., (-13.6+12.75)eV=-0.85 eV
The photons of energy 12.75 eV can excite the fourth the level of H-atom . Therefore six lines will be emitted
`((n(n-1))/(2)"lines")`