Class 12 NEET Chemistry D And F Block Elements Questions

Concept: Hypo ($\mathrm{Na_2S_2O_3}$) acts as a fixing agent in the photographic process.Explanation:In photography, after the film is developed, the unexposed and undecomposed silver bromide ($\mathrm{AgBr}$) must be removed to make the image permanent. Hypo (sodium thiosulfate) is used for this purpose. It reacts with the undecomposed $\mathrm{AgBr}$ to form a water-soluble complex, sodium dithiosulfatoargentate(I), which is then washed away.The reaction is:$$\mathrm{AgBr} + 2\mathrm{Na_2S_2O_3} \rightarrow \mathrm{Na_3[Ag(S_2O_3)_2]} + \mathrm{NaBr}$$Answer:Option C