Noble gases (Group 18 in the periodic table) have the follow-
ing volume concentrations in dry air: He, 5.24 ppm; Ne, 18.2 ppm;
Ar, 0.934 vol%; Kr, 1.14 ppm; Xe, 87 ppb.
(a) A concentration of 5.24 ppm He means 5.24 mL of He per liter
of air. Using the ideal gas law in Problem 1-18, find how many
moles of He are contained in 5.24 mL of He at 25.008C (298.15 K)
and 1.000 bar. This number is the molarity of He in the air.
(b) Find the molar concentrations of Ar, Kr, and Xe in air at 258C
and 1 bar.