Question

counting valence electrons
how many valence electrons does this oxygen atom have?
eight
two
four
six

Explanation:

Step1: Identify valence shell

Valence electrons occupy the outermost electron shell. For the given oxygen atom diagram, the outermost (largest) ring is the valence shell.

Step2: Count electrons in valence shell

Count the green dots (electrons) on the outermost ring: $6$ electrons.

Answer:

six