a) Air pollution is the presence of one or more contaminants in such quantities, such characteristic and of such duration in the atmosphere that may tend to be injurious to human beings, plants and animals, or cause damage to the properties. Explain THREE (3) criteria that used to classify air pollutants. b) A petroleum refinery industry plans to change the scrubbers to a cyclone collector for particulates removal. An air stream with a flow rate of 7 m/s is passed through a cyclone standard proportions with a standard-dimension cyclone with five of effective turn. The diameter of the cyclone is 2.4 m and the air temperature is 77C. i) Determine the removal efficiency for a particle with a density of 1.2 g/cm and a diameter of 20 m. ii) Determine the collection efficiency based on i), if a bank of 62 cyclones with diameters of 20 cm are used.