Question

at the same temperature which of the following gases contains molecules with the slowest average velocity?

A) NO2

B) CO

C) CO2

D) NO

E) the average velocity is the same

Answer 1

rms(root mean square) velocity of gases is defined by

Urms 3RT M

Most probable velocity

2RT Ump VM

Average velocity $v_{av}=\sqrt{\frac{8RT}{\pi M}}$

Where, M= molar mass of gas, T= temperature, R = universal gas constant

So at same temperature as the molar mass increases average velocity decreases.

So trend of molar mass is

So trend of average speed will be $v_{av}(CO)>v_{av}(NO)>v_{av}(CO_2)>v_{av}(NO_2)$

Answer:

A) NO2 has slowest average velocity.