Ar (g) is placed in a 3.80 L container at 320 K. The gas pressure is 0.496 atm.

PV=nRt

Therefore n (number of moles) = PV/RT

=> (0.49*3.80) / (0.08206*320)

Therefore Number of moles is = 0.071mols

Explanation: By using the Real gas equation ...

PV=NRT.

We can solve for the number of moles of Ar by making N the subject ...

Always make sure you pressure is In atm, your Volume is in Litres and temperature in degree Kelvin.

Also Recall the universal gas constant R used in this type of questions which is 0.08206.

Hence l, by making N the subject we get our answer as