2. A gas is contained in a rigid tank at pressure P, and temperature To. The surroundings' pressure is Po and the temperature To. The tank is connected to a vacuum pump which sucks out the gas into the surroundings. The pump can decrease the pressure down to P., when the gas temperature changes to T... Tank Po. To PiTo Po, To Vacuum pump Assume that the tank's wall is insulating, and the gas is withdrawn quickly. (a) Write the first law of thermodynamics for the evacuation, defining necessary quantities. (b) Solve the equation you have derived in (a). Express T. with To, Po, Poo, and y = p/y. Does the temperature rise or drop? =