Question

multiple choice question
the noble gases are stable because they
o each have a full outer energy level
do not mix well with other elements
have very low boiling points
have relatively high atomic masses

Explanation:

Noble gases are stable because of their electron configuration. The octet rule (or duet rule for helium) states that atoms are stable when their outer energy level is full. Noble gases have a full outer energy level (either 2 or 8 electrons in the valence shell), which makes them less likely to gain, lose, or share electrons. The other options are incorrect: "do not mix well with other elements" is a consequence of their stability, not the cause; "very low boiling points" is a physical property related to weak intermolecular forces, not chemical stability; "relatively high atomic masses" has no direct relation to chemical stability.

Answer:

each have a full outer energy level