You are working in a lab with a stable, unreactive element. How many valance electrons does this element have?

4

6

2

8

8

Explanation:

The element must have a complete octet in order to be unreactive.

Such an unreactive element must be a noble gas / inert gas / or group O element.

Most elements on the periodic table try to mimic them.

This configuration makes the group O elements unique and unreactive.

What drives reactively is ability of an atom to lose or gain electron in order to achieve a stable configuration such as that of group O elements.