When 0.526 L of Ar at 1.20 atm and 227°C is mixed with 0.270 L of O2 at 501 torr and 127°C in a 400. mL flask at 27°C, what is the pressure in the flask?

Answer 1

Convert Ar to moles using PV = nRT
Do the same for O2. Add the moles together and use PV = nRT again with 400 mL final volume (converted to L of course).