Agas cylinder is filled with 4.00 moles of oxygen gas at 300.0 k. the piston is compressed to yield a pressure of 400.0 kpa. what is the volume inside the cylinder?

To answer this item, it is assumed that the gas in the cylinder is ideal such that it follows the equation,
                                        PV = nRT
when V is to be calculated,
                                              V = nRT/P
        V = (4)(0.0821 L.atm/molK)(300 K) / (400 kPa/101.325 kPa/atm)  
                                                V = 24.95 L
Thus, the volume of gas in the cylinder is 24.95 L.