The mass of hydrogen molecules is 3.32 * 10^-24 gm. If 10^23 H2 molecules strike 2 sq. cm per secondwith the velocity of 10^5 cm/s at an angle of 45 degree to the normal to the wall, then the exerted pressure will be..???

Ans is : 2350 N/m^2

I need to know that where to use the 10^23 H2 molecules count. Can u please explain me in detail...

Dear student,

While finding out the pressure, you will be needed to find out the force, which is rate of change of momentum. The momentum of the hydrogen molecules is dependent on the total mass of all the hydrogen molecules colliding. Hence you need to multiply the number of hydrogen striking the wall with the mass of individual hydrogen molecule to find out the total mass of colliding hydrogen molecules.