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⚛️ Physics  ·  Atoms  ·  NEET & JEE

In Bohr’s model, the angular momentum of an orbiting electron is quantised in units of:

Answer: h/2π.

  • A h/2π
  • B h itself
  • C 2πh
  • D h squared

Correct answer: A. h/2π

Explanation: Bohr’s condition: angular momentum = nh/2π.

Comparison of the Thomson model and the Rutherford model of the atom: in the Thomson plum pudding model alpha particles pass almost straight through a diffuse positive sphere, while in the Rutherford model a concentrated central nucleus deflects some alpha particles through large angles, with the lower panels showing the alpha particle source and gold foil and the observed result of wide-angle scattering

The Geiger–Marsden alpha-scattering result: a few alpha particles bounce back at large angles, which rules out Thomson’s diffuse model and demands a tiny, massive, positively charged nucleus. Image: Kurzon, CC BY 3.0, via Wikimedia Commons.

Concept context

Thomson's plum-pudding model, Rutherford's nuclear model from alpha-scattering, Bohr's postulates and hydrogen spectrum, spectral series (Lyman to Pfund), Rydberg formula, and limitations of each model.

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