Question

Which one of the following reactions represents developing in photography?

• A. $ AgN{{O}_{3}}+NaBr\xrightarrow{{}}AgBr+NaN{{O}_{3}} $
• B. $ AgBr+2N{{a}_{2}}{{S}_{2}}{{O}_{3}}\xrightarrow{{}} $ $ N{{a}_{3}}[Ag{{({{S}_{2}}{{O}_{3}})}_{2}}]+NaBr $
• C. $ AgBr+hv\xrightarrow[{}]{{}}AgB{{r}^{*}} $
• D. $ {{C}_{6}}{{H}_{4}}{{(OH)}_{2}}+2AgB{{r}^{*}}\xrightarrow[{}]{{}}{{C}_{6}}{{H}_{4}}{{O}_{2}} $ $ +2HBr+2Ag $
• E. $ AgBr+2N{{H}_{3}}\xrightarrow[{}]{{}}[Ag{{(N{{H}_{3}})}_{2}}]Br $

Answer 1

Answer: (D)

$ \underset{quinol}{\mathop{{{C}_{6}}{{H}_{4}}{{(OH)}_{2}}}}\,+2AgB{{r}^{*}} $
$ \xrightarrow[{}]{{}}\underset{quinone}{\mathop{{{C}_{6}}{{H}_{4}}{{O}_{2}}}}\,+2HBr+2Ag $ reaction represents developing in photography. Because in developing in photography quinol $ {{C}_{6}}{{H}_{4}}{{(OH)}_{2}} $ is used as mild reducing agent to reduce more silver bromide to silver. It is done to make silver visible.