Hydrogen atom in ground state is excited by a monochromatic radiation of `lambda=975Å` . Number of spectral lines in the results spectrum emitted will be

Options

A. 3
B. 2
C. 6
D. 10

Answer

C

Explanation

Energy of the photon
`E = (hc)/(lamda) = (1240)/(97.5) =12.75 eV`
This energy is equal to energy gap between `n =1(-13.6)` and `n = 4(-0.85)`. So by this energy. The electron will excite form n =1 to n = 4. When the electron will fall back. number of spectral lines emitted.
`=(n(n-1))/(2)=((4)(4-1))/(2)=6`.