Raul Navarro, age 13, of San Antonio, Texas, for his 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 tasteless, odorless and colorless.

Inert gases are also extremely stable. That is, they rarely combine with other elements. They are sometimes called noble gases for this reason, and rare gases because they are not relatively abundant.

The various inert gases have few, but important, uses. Argon is used to fill light bulbs, while neon and other inert gases are used to fill neon signs. Helium is often used in breathing mixtures for divers and also in weather balloons because it is much lighter than air.

Liquid helium is used in low temperature research.