AP Chemistry Exam Prep

Category - AP Chemistry

The emission spectrum of an element is:
  1. The spectrum given off by a heated gas when its excited electrons release photons
  2. The spectrum observed from a cool gas, where black lines on the spectrum indicate photons used to excite electrons
  3. The spectrum given off by a cool gas when its excited electrons release photons
  4. The spectrum observed from a heated gas, where black lines on the spectrum indicate photons used to excite electrons.
  5. The range of gases emitted during a chemical reaction.
Explanation
Answer: A is the correct answer because it is the definition of an emission spectrum. Emission spectra show bands of colored light emitted by an excited/heated gas as the electrons relax from their excited state back to their normal state. This relaxation releases a photon of light corresponding to the energy change from excited to relaxed state. B is an absorption spectrum. The other answers are completely made up and false.
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