Answer: T is proportional to n 3.
- A T is proportional to n
- B T is proportional to n<sup>3</sup>
- C T is proportional to n<sup>2</sup>
- D T is proportional to 1/n
Correct answer: B. T is proportional to n<sup>3</sup>
Explanation: In the Bohr model, r is proportional to n<sup>2</sup> and v is proportional to 1/n. Since T = 2πr/v, T is proportional to n<sup>3</sup>.

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.