Noble gas and Rn

Noble gas noun - Any of the chemically inert gaseous elements of the helium group in the periodic table.

Rn and noble gas are semantically related. In some cases you can replace term "Rn" with "Noble gas", this terms are similar.

Rn noun - A radioactive gaseous element formed by the disintegration of radium; the heaviest of the inert gasses; occurs naturally (especially in areas over granite) and is considered a hazard to health.

Noble gas and Rn are semantically related. You can use "Noble gas" instead a noun "Rn".