Ionization potential of hydrogen atom is 13.6 eV. Hydrogen atoms in the ground state are excited by monochromatic radiation of photon energy 12.1 eV. According to Bohr's theory, the spectral lines emitted by hydrogen will be

Options

A. two
B. three
C. four
D. one

Answer

B

Explanation

Ionization energy corresponding to ionization potential =-13.6eV
Photon energy incident =12.1eV
So, the energy of electron in excited state
`=-13.6+1.21=-1.5eV`
`ie, E_(n)=-(13.6)/(n^(2))eV`
`-1.5=(-13.6)/(n^(2))`
`Rightarrow n^(2)=(-13.6)/(-1.5)approx 9`
`therefore n=3`
ie, energy of electron in excited state corresponds to third orbit.
The possible spectral lines are when electron jumps from orbit 3rd to 2nd, 3rd to 1st and 2nd to 1st. Thus, 3 spectrual line are emitted.