In which year did Niels Bohr propose a theory for the hydrogen atom based on the quantum theory that some physical quantities take only discrete values?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 1913.
In 1913, Niels Bohr integrated quantum theory with Rutherford's atomic model. He proposed that electrons orbit the nucleus only in specific, discrete energy levels or orbits, without radiating energy. Electrons can jump between these quantized orbits by absorbing or emitting energy in the form of photons, with the energy difference corresponding to the photon's energy. This model successfully explained the discrete spectral lines observed in the hydrogen atom's emission spectrum, a key observation that classical physics could not account for.