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Which of the following postulate of Bohr's model of hydrogen atom is not in agreement with quantum mechanical model of an atom? (1) The electron in atom's stationary state moves in a circle around the nucleus. (2) An atom in a stationary state does not emit electromagnetic radiation as long as it stays in the same state. (3) When an electron makes a transition from a higher energy stationary state to a lower energy stationary state, then it emits a photon of light. (4) An atom can take only certain distinct energies E1, E2, E3, etc. These allowed states of constant energy are called the stationary states of atom.

1. The electron in atom's stationary state moves in a circle around the nucleus.
2. An atom in a stationary state does not emit electromagnetic radiation as long as it stays in the same state.
3. When an electron makes a transition from a higher energy stationary state to a lower energy stationary state, then it emits a photon of light.
4. An atom can take only certain distinct energies E1, E2, E3, etc. These allowed states of constant energy are called the stationary states of atom.

Correct answer: The electron in atom's stationary state moves in a circle around the nucleus.

Solution

The quantum mechanical model describes electrons as existing in probabilistic orbitals rather than fixed circular paths, which contrasts with Bohr's assumption of circular orbits for stationary states.

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