CCl4 is used as fire extinguishers under the name of pyrene.
The dense vapours of carbon tetrachloride forms a protective layer on the burning objects and avoids the oxygen or air to come in contact with the fire from the burning objects and provides incombustible vapours.
Chemical paint strippers that include methylene chloride and phenol have been extensively used to remove polymer coatings from metallic substrates. These strippers are inexpensive and remove polymeric organic coatings quickly and easily from a variety of metallic substrates without damage to the substrate.
Dichlorodiphenyltrichloroethane (DDT) is an organic halogen that acts by killing insects rapidly upon contact. DDT is harm to all biota of the planet as it is non-biodegradable, and tends to become more concentrated as it moves up the food chain.
The freons are simple fluorinated and aliphatic organic compounds that contain fluorine, carbon, hydrogen, chlorine, bromine etc. These are used as the refrigerants and propellants. Chlorofluorocarbons, Hydrochlorofluorocarbons are the types of freons. They have a low boiling point and low suface tension due to which they are used in refrigerators, air conditioners etc. However, they undergo photo-dissociation when exposed to the UV rays, releasing a reactive chlorine ion that is capable of reacting with ozone. This reaction is responsible for the depletion of the ozone in the stratosphere. Hence, the correct answer is 'Freon'.
Hence, CCl4 used in fire extinguisher. CH2Cl2 used as paint remover. Freons used in refrigerator and AC.DDT used as non Biodegradable insecticide.