When a 1.00 L flask containing 0.500 atm of gas A is joined with a 2.00 L flask containing 0.850 atm of gas B, and the stopcock between the flasks is opened, and the gases are allowed to mix thoroughly, the following reaction proceeds at constant temperature. What is the resulting total pressure of gases in now-joined flasks after the reaction proceeds to completion?
2A(g) + B(g) ? A2B(g)
A. 0.167 atm
B. 0.350 atm
C. 0.0835 atm
D. 0.567 atm