Whenever a hydrogen atom emits a photon in the Balmer series .

Options

A. It may emit another photon in the Balmer series
B. It must emit another photon in the lyman series
C. the second photon, if emitted, will have a wavelength of about `122 nm`
D. It may emit a second photon, the wavelength of this photon cannot be predicted

Answer

B, C

Explanation

Any traansition causing a photon to be emitted in the Balmer series must end `n = 2`. The must be followed by the transition from `n = 2 to n = 1`, emitting a photon of energy `10.2 eV,which corresponds to a wavelength of about `122 nm`. This belongs to the Lyman series.