Particles having size 10m and density 2g/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 4cm. Inside the chamber, scrubbing liquid and polluted air are flowing at 20L/s and 25m3/s, respectively. Superficial gas velocity can be assumed to be 0.2 m/s. Droplet diameter for separation is 0.5mm. Atmospheric pressure and standard temperature are present inside the chamber. Assume terminal settling velocity of the droplets to be 300cm/s and neglect settling velocity of particle. Estimate the efficiency of the spray chamber (in whole numbers), assuming (i) 100% and (ii) 50% spray utilization. (iii) How does efficiency vary with spray utilization. [4+4+2=10]