Which of the following is an example of a noble gas?

Neon is an example of a noble gas because it belongs to Group 18 of the periodic table, which is characterized by stable electron configurations that result in very low reactivity. Noble gases, including neon, argon, krypton, xenon, and radon, have filled outer electron shells, making them non-reactive under standard conditions. This stability is what defines their classification as noble gases. Neon, in particular, is commonly used in lighting because it emits a bright glow when electrified.

In contrast, oxygen is a diatomic molecule essential for respiration but is highly reactive. Carbon, known for its versatility in forming various compounds, is a fundamental building block of life and is also reactive. Sodium, a highly reactive metal, is known for readily losing an electron to form positive ions. Understanding these distinctions illuminates why neon fits into the category of noble gases while the others do not.