How can you determine the number of moles of a contained gas when the pressure, volume, and temperature are known values?

Answer: use the ideal gas equation, PV = nRT

Explanation:

The ideal gas equation permits you to determine one variable, P, V, n or T, when you know the other two variables.

In this case, your are told you know P, V and T, so you can solve for n:

n = PV / (RT)

Remember this:

R is the universal constant of gases, and you must use the adequate units.

T is the temperature in absolute scales, i. e Kelvin.