Krypton is a colorless, odorless gas. It has a boiling
point of -152.9°C (-243.2°F) and a density of 3.64
grams per liter.
That makes krypton about 2.8 times as dense as air.
SECONDLY, Krypton is one of the rarest gases on Earth, composing only 1 part per million of the atmosphere by volume. This noble gas is colorless and odorless. It has a full outer shell of electrons, rendering it largely inert to reactions with other elements.
