Which of the following is/are not TRUE for the Bohr's atomic model?A.…

The correct answer is Option (3) → C and D only

Bohr’s model works only for a single electron round a nucleus: it gives the energy levels and line frequencies, but cannot treat electron–electron interaction or line intensities.

(A) Bohr’s model predicts the frequencies of the light emitted by hydrogenic atoms. — Correct statement. A jump between two levels emits \( \nu = (E_i - E_f)/h \), matching the hydrogen lines.

(B) The Bohr model is applicable to the hydrogen like atoms. — Correct statement. It applies to one-electron systems such as H, He⁺ and Li²⁺.

(C) Bohr’s model could also explain the relative intensity variations of hydrogen spectrum. — Incorrect statement. The model gives no transition probabilities, so it cannot explain line intensities.

(D) Bohr’s model can also be extended to more than one electron atoms like Helium — Incorrect statement. It cannot account for the repulsion between helium’s two electrons.

Note: It seems that there is a mistake in the original NTA paper, which prints “A, B and E only” in Option (1), although the question has no statement E. The question can still be solved, because only statements C and D are not true.

NCERT (2026-27):
Summary – “… Bohr’s model is applicable only to hydrogenic (single electron) atoms. It cannot be extended to even two electron atoms such as helium. This model is also unable to explain for the relative intensities of the frequencies emitted even by hydrogenic atoms.”