a cyinder with a volume of 5.37 liters contains N2 at a pressure of 2.82 atm at 26 celcius. how many grams Ne must be added to raise the total pressure to 7.5 atm
Note the correc spelling of celsius.
Use PV = nRT to calculate n for N2.
Use PV = nRT, substituting 7.5 atm for pressure to calculate n for total number of molecules. Delta n will be the number of Ne moles that must be added and convert moles Ne to grams. You may want to check to see that the pressure is increased by the appropriate amount.