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

Options

A. 1
B. 4
C. 2
D. 6

Answer

D

Explanation

Energy of excited level
`= -13.6 + 12.75 = - 0.85 eV`
`E_(n)= (-13.6)/(n^(2)) rArr - 0.85 = (-13.6)/(n^(2)) rArr n= 4`
No. of spectral lines `= (n(n-1))/(2)= (4 xx 3)/(2)= 6`