A solution was prepared by dissolving 16.17 g of an unknown substance in 200 g of benzene and the freezing point of the solution was measured as 2.67 C. Kf value and freezing point of pure benzene are -5.12C/m and 5.49C, respectively. a) Calculate the molecular weight (MW) of the unknown. b) In a separate analysis of the unknown, was found to contain 49.0% carbon, 48.2% chlorine, and 2.75% hydrogen. What is the molecular formula of the unknown?