Question

why are noble gases considered stable? they have incomplete electron shells. they have a high reactivity with other elements. they have a full outer electron shell. they can easily gain or lose electrons.

Explanation:

Noble gases are stable because their outer - most electron shell is full. This gives them a stable electron configuration and makes them less likely to participate in chemical reactions. Incomplete electron shells, high reactivity, or the ability to easily gain or lose electrons would make an element less stable.

Answer:

They have a full outer electron shell.