Place the following gases in order of increasing average molecular speed at 25 °C: CHCl3, SF6, Xe, CCl2F2.?

Molar mass of CHCl₃ = (12.0 + 1.0 + 35.5×3) g/mol = 119.5 g/mol
Molar mass of SF₆ = (32.1 + 19.0×6) g/mol = 146.1 g/mol
Molar mass of Xe = 131.3 g/mol
Molar mass of CCl₂F₂ = (12.0 + 35.5×2 + 19.0×2) g/mol = 121.0 g/mol

For a gas at constant temperature, the smaller the molar mass, the greater the average molecular speed is.
Molar mass : SF₆ > Xe > CCl₂F₂ > CHCl₃
Average molecular speed at 25°C : SF₆ < Xe < CCl₂F₂ < CHCl₃

XE , SF6, XE, CCl2F2, CHCL3