Study the following passage and answer the questions. Halogens in their reactions among themselves and with a variety of other elements give rise to a large number of compounds. Halogen derivatives and interhalogen compounds represent major type of halogen compounds.  A “black and white” photographic film contains a coating of silver bromide on a support such as cellulose acetate. During the developing process the unexposed AgBr is washed away by complexation of Ag(I) by sodium thiosulphate solution. These washings are often disposed of as waste. However metallic silver can be recovered from them by adding cyanide, followed by zinc. The most reactive halogen (fluorine) reacts with other halogens Cl2Br2  and I2  under controlled conditions giving tetra-atomic, hexa-atomic and an octa-atomic molecule, respectively. Chlorine acts as a strong oxidizing agent and can oxidize hypo, while chlorine dioxides reacts with the alkali.The chemical equation for the oxidation of sodium thiosulphate to an ion containing the highest oxidation state of sulphur by chlorineThe photochemical reaction that occurs when light falls on AgBr(s) coated on a film is