An evacuated glass vessel weighs 40.0 g when empty, 135.0 g when filled with a liquid of density 0.95 g mL-1 and 40.5 g when filled with an ideal gas at 0.82 atm at 250 K. The molar mass of the gas in g mol-1 is:
(Given: R = 0.082 L atm K-1 ' mol-1')
(A) 35
(C) 75
(B) 50
(D) 125
