Particles having size 10 um and density 2 g/cc are contained in a sample of polluted air (viscosity-0.00018 poise). This sample is passed through a vertical counter-current spray chamber at a contact zone of 4 cm. Inside the chamber, scrubbing liquid and polluted air are flowing at 20 L/s and 25 m/s, respectively. Superficial gas velocity can be assumed to be 0.2 703 m/s. Droplet diameter for separation is 0.5 mm. Atmospheric pressure and standard temperature are present inside the chamber. Assume terminal settling velocity of the droplets to be 300 cm/s and neglect settling velocity of particle. Estimate the efficiency of the spray chamber in whole numbers assuming 1)100% 2) 50% spray utilisation 3) how does efficiency vary with spray utilization.