Write balanced chemical equation for developing a black and white photographic film. Also give reason why the solution of sodium thiosulphate on acidification turns milky white and give balance equation of this reaction

When a PHOTOGRAPHIC FILM is treated with HYPO,the AgCl on the film reacts with the Na2S2O3 forms a complex Na3[Ag(S2O3)] along with NaBr.
Hence the reaction is AgCl+Na2S2O3——->Na3[Ag(S2O3)]+NaBr.
When HYPO is reacted with SULPHURIC ACID,it forms Sodium Sulphate along with Sulphurdioxide and Sulphur along with water.
Na2S2O3+2H2SO4——->Na2SO4+SO3+S+4H2O