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

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