Home MCQs NEET Chemistry Question #7381
Back to Questions
NEET Chemistry QUESTION #7381
Question 1
In a hydrogen atom, electron transitions occur from \(n=5\) to \(n=2\), emitting a photon of wavelength 434 nm. What will be the wavelength of the photon emitted when the electron transitions from \(n=4\) to \(n=2\)?
  • 586.16 nm
  • 48.608 nm
  • 486 nm✔️
  • 400.16 nm
Correct Answer Explanation
Using Rydberg formula: \(\dfrac{1}{\lambda} = R_H\left(\dfrac{1}{n_1^2} - \dfrac{1}{n_2^2}\right)\)

For \(n=4 \to n=2\) (H\(\beta\) line of Balmer series): \(\dfrac{1}{\lambda} = R_H\left(\dfrac{1}{4} - \dfrac{1}{16}\right) = R_H \times \dfrac{3}{16}\)

This gives \(\lambda \approx 486\) nm (blue-green, visible Balmer series H\(\beta\) line). The 434 nm line (\(n=5\to2\)) is H\(\gamma\). These are well-known spectral lines of hydrogen.