Which of the following transitions gives photon of maximum energy?

Options

A. `n=2` to `n=6`
B. `n=6` to `n=2`
C. `n=2` to `n=1`
D. `n=1` to `n=2`

Answer

C

Explanation

Whenever an atom gets de-excited from higher to the lower orbit, it radiation of a given frequency
`DeltaE=hfimplies f prop DeltaE`
The photons of highest frequency will be emitted, for the transition in which `DeltaE` is maximum, i.e., from 2 to 1.