34 grams Iodo propane is treated with alcoholic KOH. What mass of propene is obtained if yield of the product is 50%(AW of Iodine=127)

C3H7I + KOHalc→CH3CH=CH2+KI+H2O; 170 g                                      42 g   34 g                                         ? Propene formed when the yield is 100%= 42×34170=8.4gm; Since the yield is 50% , propene formed =8.4×0.5=4.2 gm