What volume is occupied by #4.02 * 10^22# molecules of helium gas at STP?
The molar volume of an ideal gas at STP is
In one mole of gas there are Avogadro's number of particles. There are
So how many moles are there in
It is simply the quotient:
The volume of course is the prior quotient mulitplied by the molar volume of an ideal gas: