A rigid tank contains 5.56 kg of an ideal gas at 3.6 ATM and 40 degrees Celsius. Now a valve is opened and half of the mass of the gas is allowed to escape. If the final pressure in the tank is 2.0 ATM, the final temperature of the tank is?
A. -99.1 degrees Celsius
B. 44.4 degrees Celsius
C. 20 degrees Celsius
D. 74.8 degrees Celsius