Explain if a water tower containing 4000 m3 of water has been taken out of service to install a chlorine monitor. If the concentration of chlorine in the water tower was 2.0 mg/L while the tower was taken out of service. If the chlorine decays by first-order kinetics with a rate constant k=1.0 d-1, explain what is the chlorine concentration when the tank is put back in service eight hours later? Explain what mass of chlorine in kg must be added to the tank to raise the chlorine level back to 2.0 mg/L? You may presume the tank is a completely mixed batch reactor.