SAT Subject Physics Practice Question 140: Answer and Explanation

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Question: 140

3. An atom with one electron has an ionization energy of 25 eV. How much energy will be released when the electron makes the transition from an excited energy level, where E = –16 eV, to the ground state?

A. 9 eV
B. 11 eV
C. 16 eV
D. 25 eV
E. 41 eV

Correct Answer: A

Explanation:

If the atom’s ionization energy is 25 eV, then the electron’s ground-state energy must be –25 eV. Making a transition from the –16 eV energy level to the ground state will cause the emission of a photon of energy.

E = (–16 eV) – (–25eV) = 9 eV

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