JEE Main 2026 Jan 21 Shift 2, Chemistry Q1: Bohr's Atomic Model

JEE Main2026Jan 21, Shift 2Chemistry

Consider the following spectral lines for atomic hydrogen:

A. First line of Paschen series

B. Second line of Balmer series

C. Third line of Paschen series

D. Fourth line of Bracket sereis

The correct arrangement of the above lines in ascending order of energy is:

A
D < C < A < B
B
A < B < C < D
C
C < D < B < A
D
D < A < C < B

Solution

Photon energy for a transition: $Δ E = 13.6 Z^{2} (\frac{1}{n _{1}^{2}} - \frac{1}{n _{2}^{2}})$ eV. List the $(n_{1}, n_{2})$ for each line and compute the bracketed factor:

A. Paschen 1st line: $n_{1} = 3, n_{2} = 4$ → $\frac{1}{9} - \frac{1}{16} \approx 0.0486$ .

B. Balmer 2nd line: $n_{1} = 2, n_{2} = 4$ → $\frac{1}{4} - \frac{1}{16} = 0.1875$ .

C. Paschen 3rd line: $n_{1} = 3, n_{2} = 6$ → $\frac{1}{9} - \frac{1}{36} \approx 0.0833$ .

D. Bracket 4th line: $n_{1} = 4, n_{2} = 8$ → $\frac{1}{16} - \frac{1}{64} \approx 0.0469$ .

Ascending energy: D < A < C < B.

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JEE Main 2026 Jan 21 Shift 2, Chemistry Q1: Bohr's Atomic Model

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