P5-158 The gaseous reaction A - B has a unimolecular reaction rate constant of 0.0015 min.at 80F. This reaction is to be carried out in parallel tubes 10 ft long and 1 in. inside diameter, under a pressure of 132 psig at 260F. A production rate of 1000 lb/h of B is required. Assuming an activation energy of 25,000 cal/mol, how many tubes are needed if the conversion of A is to be 90%? Assume perfect gas laws. A and Beach have molecular weights of 58. Source: From California Professional Engineers' Exam