13. The value of lim (A) C+1 1-e-c(1-x) x11-xec(1-x) is C (B) c+1 (C) (D) c C c+1 14. In a concentric tube counter-flow heat exchanger, hot oil enters at 102C and leaves at 65C. Cold water enters at 25C and leaves at 42C. The log mean temperature difference (LMTD) is C (round off to one decimal place). 15. A sheet metal with a stock hardness of 250 HRC has to be sheared using a punch and a die having a clearance of 1 mm between them. If the stock hardness of the sheet metal increases to 400 HRC, the clearance between the punch and the die should be mm.