Mary Ellen Olson, age 12, of Brownsville, Texas, for her question:

WHAT IS INERT GAS?

Inert gas is a name given to six chemical elements: argon, helium, krypton, neon, radon and xenon. The inert gases are all colorless, odorless and tasteless.

All inert gases are also extremely stable. This means that they rarely combine with other elements. They are sometimes called noble gases for this reason, and rare gases because they are not relatively abundant.

All the inert gases were discovered in a period of six years from 1894 to 1900. Chemists called them inert because they believed the gases never combined with other elements. However, during the 1960s, chemists combined them with other elements, so the term is not strictly accurate. The gases have few, but important, uses.