Arrange the following Spectral series with lower energy state quantum…

The correct answer is Option (2) → D, A, B, C, E

A spectral series of hydrogen is the set of lines produced when electrons fall to one particular lower level, whose quantum number is \( n_f \). The series are named after the lower level to which the electron drops.

    D. Lyman series: \( n_f = 1 \)
    A. Balmer series: \( n_f = 2 \)
    B. Paschen series: \( n_f = 3 \)
    C. Brackett series: \( n_f = 4 \)
    E. Pfund series: \( n_f = 5 \)

Arranged for \( n_f = 1, 2, 3, 4, 5 \), the order is D, A, B, C, E.

Note: A similar question was also asked in CUET (UG) 2023 on 25-05-2023 (Slot 3).

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):
Summary – “… 6. The atomic hydrogen emits a line spectrum consisting of various series. The frequency of any line in a series can be expressed as a difference of two terms;

Lyman series:

    \( \displaystyle \nu = Rc\left(\frac{1}{1^2} - \frac{1}{n^2}\right);\ n = 2, 3, 4, \ldots \)

Balmer series:

    \( \displaystyle \nu = Rc\left(\frac{1}{2^2} - \frac{1}{n^2}\right);\ n = 3, 4, 5, \ldots \)

Paschen series:

    \( \displaystyle \nu = Rc\left(\frac{1}{3^2} - \frac{1}{n^2}\right);\ n = 4, 5, 6, \ldots \)

Brackett series:

    \( \displaystyle \nu = Rc\left(\frac{1}{4^2} - \frac{1}{n^2}\right);\ n = 5, 6, 7, \ldots \)

Pfund series:

    \( \displaystyle \nu = Rc\left(\frac{1}{5^2} - \frac{1}{n^2}\right);\ n = 6, 7, 8, \ldots \)”