1. As an electron in an atom moves from a higher energy state to a lower energy state, the atom (A) becomes a negative ion
(C) releases energy
(B) becomes a positive ion
(D) absorbs energy

(C) releases energy

From Bohr's model of the atom:

We can understand the energy transitions involved when an electron moves from one energy level to another.

An electron in an energy level has a definite amount of energy associated with it at that level. When electrons change state, they must absorb or emit the exact amount of energy which will bring them from initial to final states. When the electron is excited, it moves from the ground state to an excited state, it must must absorb energy. On returning from an excited state, energy is released or emitted.

Therefore, option C is correct.

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(C) releases energy

Explanation:

From Bohr's model of the atom, we can understand the energy transitions involved when an electron moves from one energy level to another.

An electron in an energy level has a definite amount of energy associated with it at that level. When electrons change state, they must absorb or emit the exact amount of energy which will bring them from initial to final states. When the electron is excited, it moves from the ground state to an excited state, it must must absorb energy. On returning from an excited state, energy is emitted.

Active transport requires energy.