The ratio of wavelengths of the last line of Balmer series and the last line of Lyman series is :

1. 1

2. 4

3. 0.5

4. 2

Doubtly Asked 30 Oct 2026 NEET UG 2017 Practice test neet Save WhatsApp Report

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Answer: 2. 4

Key idea: the last line of a series has \(n_2=\infty\): \(\dfrac1\lambda=RZ^2\left(\dfrac1{n_1^2}-0\right)\).

Balmer (\(n_1=2\)): \(\dfrac1{\lambda_B}=\dfrac R4\). Lyman (\(n_1=1\)): \(\dfrac1{\lambda_L}=R\).

\(\dfrac{\lambda_B}{\lambda_L}=\dfrac{R}{R/4}=4\).

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report

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