⚛️ Physics · Atoms · NEET & JEE

What minimum energy must a hydrogen atom in its ground state absorb to reach the n = 2 state?

Answer: 10.20 eV.

A 3.40 eV
B 12.09 eV
C 10.20 eV
D 13.60 eV

Correct answer: C. 10.20 eV

Explanation: The ground-state energy is -13.6 eV and the n = 2 energy is -13.6/4 = -3.40 eV. Therefore the required excitation energy is 10.20 eV.

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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What minimum energy must a hydrogen atom in its ground state absorb to reach the n = 2 state?

Concept context

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