A solution containing 15.3 g of an unknown compound dissolved in 36.0 g of H2O was found to have a vapor pressure of 30.4 torr at 30 C. The vapor pressure of pure water at this temperature is 31.8 torr. What is the molar mass of the unknown compound? (a) 173.8 g/mol (b) 278.5 g/mol (c) 713.1 g/mol (d) 627.4 g/mol

answer is A please show work