Ionisation potential of hydrogen atom is 13.6 eV. Hydrogen atom in ground state is excited by monochromatic light of energy 12.1 eV. The spectral lines emitted by hydrogen according to Bohr's theory will be-

Options

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

Answer

C

Explanation

Since ionisation potential of hydrogen atom is 13.6 eV, so `E_(1)=-13.6eV`
Now, `E_(n)-E_(1)=(-13.6)/(n^(2))-(-13.6)=12.1`
or `(-13.6)/(n^(2))+13.6=12.1" "therefore n=3`
After absorbing 12.1 eV energy, the electron of H-atom is excited to 3rd shell.
Thus, possible transition are 3 i.e., `3to2,2to1 and 3to1`.