Select molecules and their boiling point and molar-mass values

•ethyl acetate
-16.5°c
-88.1 g/mol
•acetonitrile
-81.6°c
-41.0 g/mol
•isopropyl acetate
-82.4°c
-60.1 g/mol
•water
-100°c
-18.0 g/mol
•ethylene glycol
-198°c
-62.0 g/mol

q1: the unknown given for analysis is one of the molecules listed in the table above. about 5 ml of an unknown
liquid was placed in a 250ml erlenmeyer flask and covered with aluminum foil. the flask was heated to
90.0°c. once most of the unknown escaped through a small hole in the aluminum foil cover, the flask was
removed and cooled. the condensed liquid weighed about 0.540 g. the flask's total volume was measured to
be 268.2ml. the barometric pressure was 758.2 torr. what is the unknown's molar mass and identity? .
[recall that 1.000 atm = 760.0 mm hg = 101.325 kpa and that r = 8.3145 kpa. l/mol. k.]

q2: what measurement is the limiting factor in the above calculation?