1. (35 marks). Consider the two series tank mixing process shown below in the following figure. The volumetric flow rate and holdup volume are constant, where the steady state values of tanks 1 and 2 are kept constant at 1.4m3 and 2.1m3 respectively. The flow rate of each process stream is 0.7m3/min. The process starts initially at steady with Ci=C1=C2= 0.4kg salt /m3. Assume that the two tanks are perfectly mixed. a) Write the modelling equations for the process to show how the concentration changes with time in both tanks. b) Perform the Degree of Freedom analysis and determine its specification. c) Find the transfer function, C2(s)/Ci(s) d) At time t=0, a step input is applied in the feed concentration, Ci(t), from 0.4kg salt /m3 to 1.4kg salt /m3. What will be the concentration leaving the second tank after 5 minutes