Which set of gases is listed from lowest to highest root-mean-square speed at 25°C?

Question

Quizplus · Accepted Answer

The root-mean-square speed of a gas is proportional to the square root of its temperature and inversely proportional to the square root of its molar mass. At 25°C, the molar masses of the gases are: Kr (83.8 g/mol), CO2 (44.0 g/mol), NO2 (46.0 g/mol), and SF6 (146.0 g/mol). Therefore, the root-mean-square speeds of the gases from lowest to highest are: SF6 < Kr < NO2 < CO2.

Which Set of Gases Is Listed from Lowest to Highest