Consider a two-stage cascade refrigeration system operating between -80oC and 80oC. Each stage operates on an ideal vapor-compression refrigeration cycle. Upper cycle use R-12 as working fluid, lower cycle use R-13. In the lower cycle refrigerant condenses at 0oC, in the upper cycle refrigerant evaporates at -5oC. If the mass flow rate in the lower cycle is 1 kg/s, determine (a) the mass flow rate through the upper cycle, (b) the amount of heat removed from the refrigerated space and (c) COP. (d) What-if Scenario: What would the COP be if we consider a one-stage ideal vapor-compression system between -80oC and 80oC with R-13 as the working fluid?