The question is incomplete, the complete question is;
Chris the Chemist was working in the lab, and he wanted to see what would happen if he put copper chloride into a Bunsen burner flame. As soon as he put it in the flame, it began to emit a green color. Which of these BEST describes this outcome?
A) The heat split the nucleus and created a new element.
B) As the copper chloride was heated, electrons were turned into neutrons.
C) As the electrons moved to a higher energy level, a photon of light is emitted.
D) When excited electrons return back to the ground state, a photon of light is emitted.
Answer:
D) When excited electrons return back to the ground state, a photon of light is emitted.
Explanation:
According to Bohr's model of the atom, electrons may absorb energy and move up to higher energy levels.
These electrons quickly return to ground state from such higher energy excited states thereby emitting the excess energy absorbed during excitation.
If the higher energy level is E2 and the ground state is E1 then the energy of the photon emitted when the electron descends from energy level E2 to E1 is;
ΔE = E2 - E1
This photon emitted accounts for the green colour of the copper salt observed when it was heated.
