Question

A certain electronic transition from an excited state
to ground state of the H, atom in one or more step
gives rise to three lines in the ultra violet region of
the spectrum. How many lines does this transition
produce in the infrared region of the spectrum :-​

Answer 1

Answer:

Let the four lines are observed in the ultraviolet region of the spectrum.

These correspond to the transitions

5→1,4→1,3→1 and 2→1

The  possible transitions in the IR region are

5→4,5→3 and  4→3

Therefore the infrared region of the spectrum, 3 lines are produced.