In case of Bohr's model of atoms, which of the following statement is incorrect?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Bohr's model correctly predicts the intensity variations in the light of different frequencies emitted by one-electron atoms, ions
Bohr's model gives the energy levels of hydrogen-like (one-electron) systems and hence the frequencies of the spectral lines. It says nothing about how often each transition occurs, so it cannot give the relative intensities of the lines.
Option (1) Bohr's model is applicable only for one electron atom/ — Correct statement. The model works only for hydrogen-like (one-electron) atoms and ions.
Option (2) Bohr's model correctly predicts the frequencies of light emitted by one electron atoms/ions. — Correct statement. The energy levels \( E_n = -13.6\,Z^2/n^2 \) eV give the frequencies \( \nu = (E_i - E_f)/h \) correctly.
Option (3) Bohr's model correctly predicts the intensity variations in the light of different frequencies emitted by one-electron atoms, ions — Incorrect statement. The model does not predict the intensity variations of the spectral lines; this needs quantum mechanics.
Option (4) Bohr's model does not consider the electron-electron interaction in an atom — Correct statement. The model treats a single electron moving round the nucleus, so electron-electron interaction is ignored; this is why it fails for many-electron atoms.
NCERT (2026-27):
De Broglie’s Explanation of Bohr’s Second Postulate of Quantisation – “… (i) The Bohr model is applicable to hydrogenic atoms. … It does not include the electrical forces between electrons which necessarily appear in multi-electron atoms.”
De Broglie’s Explanation of Bohr’s Second Postulate of Quantisation – “… (ii) While the Bohr’s model correctly predicts the frequencies of the light emitted by hydrogenic atoms, the model is unable to explain the relative intensities of the frequencies in the spectrum.”