** ANSWER IS A** As you move from left to right across Period 3, which statement is true of the number of valence electrons as you move from one main-group element to the next?
A. The number of valence electrons increases by 1.
B. The number of valence electrons decreases by 1.
C. The number of valence electrons increases by a multiple of 2.
D. The number of valence electrons decreases by a multiple of 2.

A. The number of valence electrons increases by 1.

Explanation:

As you move across any period on the periodic table, the number of valence electrons increases by a value of 1.

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