a) With reference to the relevant intermolecular forces present, explain why water and methyl amine are miscible whereas hexane and water are immiscible. (4 marks) (b) A solute has a partition coefficient (Ko) between water and chloroform of 6.00. A 50-ml sample of an aqueous solution of the solute is extracted with 25 mL of chloroform. () Calculate the extraction efficiency of this experiment. (4 marks) (1) What volume of chloroform must be used to extract 85% of the solute? (4 marks) (1) Calculate the fraction of the solute that would be extracted if four 10 ml. portions of chloroform were used (4 marks) (c) With reference to the intermolecular forces, explain how the extraction efficiency of an aqueous solution of a weakly basic drug into an organic solvent would be expected to change on changing the pH of the aqueous solution from pH 2 to pH 10. (4 marks)