3) The six noble gases thatoccur naturally are helium(He), neon (Ne), argon (Ar),krypton (Kr), xenon (Xe), andthe radioactive radon (Rn).Also known as inert gases, theymake up a group of chemicalelements with similar properties;under standard conditions,they are all odourless,colourless, monatomic gaseswith very low chemical reactivity.