Question

How many moles of helium are contained in a 2.5L vessel at 300K under a pressure of 5.35atm?

Answer 1

PV=nRT

V,R,T,,P are known. Solve for n.

Answer 2

PV=nRT
P = pressure = 5.35 atm
V = volume = 2.5 L (if it was to say mL you would have to convert to L)
n = the number of moles = x
R = 0.08021 = this is a constant and will always be the same no matter what the other variables are
T = 300 K (if this would have been in degrees C then you would have had to convert it to K which means you just add 273 to the number)