(i) Freon 12 $(CCl_2F_2)$ is • used in aerosol propellants • refrigeration • air-conditioning. (ii) DDT (p, p′- dichlorodiphenyltrichloroethane) is • used as an insecticide, • mainly used against mosquitoes. (iii) Carbontetrachloride(CCl4) is used • in manufacture of refrigerants and propellants for aerosol cans • in synthesis of chlorofluorocarbons • as degreasing agent • as cleansing agent • as a solvent in laboratories (iv) Iodoform $(CHI_3)$ is used as anantiseptic.