Question

question 7 of 41
why are noble gases, such as argon, chemically inert?
noble gases are extremely unstable.
noble gases have a full inner electron shell.
noble gases have a full outer electron shell.
noble gases are positively charged.

Explanation:

Chemical inertness of noble gases stems from their full outer electron shells, which gives them maximum stability. Atoms react to achieve a full outer shell, so noble gases (with already full outer shells) do not need to gain/lose/share electrons, making them unreactive. The other options are incorrect: noble gases are stable (not unstable), the key is the outer (not inner) shell, and they are neutral (not positively charged).

Answer:

Noble gases have a full outer electron shell.