Explanation:

Radon has a density of around 4.4 grams per cubic centimeter. Most sources consider this element to be the heaviest noble gas.

Astatine is a radioactive chemical element with the symbol At and atomic number 85. It is the rarest naturally occurring element in the Earth's crust, occurring only as the decay product of various heavier elements.

Graphite is another allotrope of carbon; unlike diamond, it is an electrical conductor and a semi-metal. Graphite is the most stable form of carbon under standard conditions and is used in thermochemistry as the standard state for defining the heat of formation of carbon compounds.