What type of molecule has the highest average speed in a room filled with gases?

[PeachBanana]

Homework Statement

The gases in this room include oxygen (molar
mass 32 g), nitrogen (28 g), water (18 g), and
carbon dioxide (44 g). Which type of molecule has
the highest average speed?

A) O2
B) N2
C) H2O
D) CO2
E) They have the same average speed.

Homework Equations

1/2 mv^2 = 3/2 kT

The Attempt at a Solution

Is the answer water because it's mass is the smallest?

 

[RTW69]

The molecular speed of gases at constant temperature varies inversely with the square root of the molecular mass. So the lightest molecule will go the fastest.

 

[PeachBanana]

Thanks for replying. Sorry if it seemed obvious - I'm doing review problems without looking at the answers.