57 degrees celcius is equal to 330 degrees kelvin
67.88 kPa is equal to 67880 Pa
85.3 liters is equal to 0.0853 m^3
Now, the equation we will use to solve this question is:
PV = nRT where:
P is the pressure of gas = 67880 Pa
V is the volume of gas = 0.0853 m^3
n is the number of moles we are looking for
R is the gas constant = 8.31441 J K-1 mol-1
T is the temperature of gas = 330 degrees kelvin
Substitute with the givens in the above equation to get n as follows:
n = (PV) / (RT)
n = (67880*0.0853) / (8.31441*330)
n = 2.11 moles