Question

determine the number of grams of Ne gas that must be added to a container in order for the volume to increase to 38.2 L at constant pressure and temperature if the container had an initial volume of 25.0 L and 2.0 moles of Ne

Answer 1

The shorter way to work this is harder to explain so let me show you the long way. First assume a value for T, use PV = nRT, and solve for P.
P = ?
V = 25.0L
n = 2 mols (we'll call this n1)
R -= 0.08206
T = 273.

After you get P, use PV = nRT again. Use the same valus for R, T, and the value you obtained for P. Solve for n = how many mols must be in the container. Call that n2.
So how many mols Ne must be added. That's n2-n2 = ? and convert to grams. g = mols x molar mass.

Answer 2

1.72