18. The density of a noble gas at STP is 1.784 g/L. Identify the noble gas. a. Xe b. Ne c. Kr d. Ar Solution Ar is the nobel gas which has density of 1.784 g/dm³ (1dm³=1L) Nobel gasses have weak forces of attraction,so their molecules remains at large distance than other elements So in a definite volume they have small mass So their density is very low..