In which transition of a hydrogen atom, photons of lowest frequency are emitted ?

Options

A. `n=2" to" n=1`
B. `n=4" to "n=4`
C. `n=4" to "n=1`
D. `n=4" to "n=3`

Answer

D

Explanation

The energy level diagram schematically looks like this. As we move to higher and higher levels, the energy increases, but the energy gap between any two levels decreases. Hence in the transition from n = 4 to n = 3, energy related will be `E_(4)-E_(3)`. And in the transition from n = 2 to n = 1, energy released is `E_(4)-E_(3) lt E_(2)-E_(1)`
`rArr" "hupsilon_(43) lt hupsilon_(21) rArr upsilon_(43) lt upsilon_(21)`.
`upsilon_(43)` is the lowest frequency emitted among the given transitions.