4) Flash vaporization process is used to vaporise 70mole% of feed which contains 65 mole% of benzene and rest is toluene. The enthalpies per mole of feed, the liquid product and the kJ vapor product are 3,6 and 28- respectively. Calculate the heat added (in kJ) per mole of mol vapor product, if bottom product contains 30 mole% of benzene. (A) 26.28 kJ/mol (B) 20.58 kJ/mol (C) 15.28kJ/mol (D) 30.28kJ/mol