JEE Chemistry 2026 Question with Solution

Given: The spectral lines are A: first line of Paschen series, B: second line of Balmer series, C: third line of Paschen series, and D: fourth line of Bracket series.

Find: The ascending order of their transition energies.

The energy of a hydrogen transition is proportional to the difference

So, compare the factor

for each line.

For A (first line of Paschen):

For B (second line of Balmer):

For C (third line of Paschen):

For D (fourth line of Bracket):

Comparing these values:

Therefore, the ascending order is D $<$ A $<$ C $<$ B.

The correct option is D.

Given: Balmer lines end at $n_1 = 2$, Paschen lines end at $n_1 = 3$, and Bracket lines end at $n_1 = 4$.

Find: Which transition has the least to greatest energy.

Transitions ending at lower final levels generally have larger energy gaps. So Balmer transitions are more energetic than Paschen transitions, and Paschen transitions are more energetic than Bracket transitions.

Now compare within the same series:

• In the Paschen series, the third line has a larger starting level than the first line, so C has greater energy than A.
• The Bracket line D ends at $n_1 = 4$, so it is expected to have lower energy than the Paschen lines.
• The Balmer line B ends at $n_1 = 2$, so it has the highest energy among these.

Thus the order becomes D $<$ A $<$ C $<$ B.

The correct option is D.