The spectral series to which the emission line belongs, when electron in the hydrogen atom jumps from 4th energy state to 2nd energy state, is :
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Balmer series
A spectral series of hydrogen is named after the lower level in which the electron ends its jump, whatever the upper level is.
Here the electron jumps from \( n = 4 \) to \( n = 2 \). All lines ending at \( n = 2 \) form the Balmer series, which lies in the visible region; this line is \( \mathrm{H}_{\beta} \).
Note: This question is from the pre-rationalised NCERT book (2022-23). The topic was removed from the latest NCERT book (2026-27), but it is still in the CUET 2026 syllabus, so do not skip it.
NCERT (Pre-rationalised edition, 2022-23):
The Line Spectra of the Hydrogen Atom – “… For hydrogen spectrum, the Balmer formula corresponds to nf = 2 and ni = 3, 4, 5, etc. The results of the Bohr’s model suggested the presence of other series spectra for hydrogen atom–those corresponding to transitions resulting from nf = 1 and ni = 2, 3, etc.; nf = 3 and ni = 4, 5, etc., and so on. Such series were identified in the course of spectroscopic investigations and are known as the Lyman, Balmer, Paschen, Brackett, and Pfund series.”