Bulb A with volume of 500 mL initially contains N2 at 0.7 atm pressure and 25?C. Bulb B, with volume of 800 mL initially contains O2 at 0.5 atm pressure and 0?C. The two bulbs are then connected, so that there is a free passage of gas between them, and the assembly is brought to a uniform temperature of 20?C. Calculate the final pressure.