The noble gas neon is used for filling neon signs. Like other noble elements, it has a full octet (complete outer energy level) of electrons, which makes the gas A. freeze at room temperature. B. react with other gases in the air. C. unlikely to combine with other elements. D. solidify at standard pressure and temperature, chiny pray-colored solid at room​

C. unlikely to combine with other elements.

Explanation:

In Chemistry, electrons can be defined as subatomic particles that are negatively charged and as such has a magnitude of -1.

Valence electrons can be defined as the number of electrons present in the outermost shell of an atom. Valence electrons are used to determine whether an atom or group of elements found in a periodic table can bond with others. Thus, this property is typically used to determine the chemical properties of elements.

Noble gases are chemical elements with eight valence electrons and as such have a full octet. Some examples are argon, neon, etc.

Hence, the full octet makes the gas (neon) unlikely to combine with other elements.

see earlier answer