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At what wavenumber does the first line of the hydrogen Balmer series occur in the atomic spectrum?
- 9R / 400 cm⁻¹
- 7R / 144 cm⁻¹
- 3R / cm⁻¹
- 5R / 36 cm⁻¹
Correct answer: 5R / 36 cm⁻¹
Solution
Wavenumber = R(1/2^2 - 1/3^2) = R(5/36) = 5R/36. Stored 9R/400 is wrong.
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