An evacuated glass vessel weighs 50 g when empty 144.0 g when filled with a liquid of density 0.47 mL−1and 50.5 g when filled with an ideal gas at 760 mm Hg at 300 K. The molar mass of the ideal gas is(Given R=0.0821LatmK−1mol−1)

volume of liquid =volume of vessel mass of liquid(w)=144-50=94 gr volume of liquid=wd=940.47=200mL =0.2L volume of vessel=volume of gas=0.2L mass of gas =50.5-50=0.5 gr According to Ideal gas equation PV= mM RT ;   M =mRTPV =0.5×0.0821×3001×0.2=61.575 gr