Q25 / 125 · BITSAT 2021 · Chemistry

The solubility of silver bromide in hypo solution involves the formation of:

  • A
    $\mathrm{Ag}_{2} \mathrm{SO}_{3}$
  • Correct answer
    B
    $\mathrm{Ag}_{2} \mathrm{~S}_{2} \mathrm{O}_{3}$
  • C
    $\mathrm{Ag}^{+}$
  • D
    $\mathrm{NH}_{4}{ }^{+}$

Solution

Hypo solution is $\mathrm{Na}_{2} \mathrm{~S}_{2} \mathrm{O}_{3}$ solution which is used in photography for fixing films \& prints. Photographic emulsions are made of AgBr. After developing, the film is put into hypo solution. This forms soluble complex with $\mathrm{Ag}$. $\mathrm{Na}_{2} \mathrm{~S}_{2} \mathrm{O}_{3}+\mathrm{Ag} \mathrm{Br} \rightarrow \mathrm{Ag}_{2} \mathrm{~S}_{2} \mathrm{O}_{3} \longrightarrow \mathrm{Na}_{2} \mathrm{~S}_{2} \mathrm{O}_{3} }{\mathrm{Na}_{5}\left[\mathrm{Ag}\left(\mathrm{S}_{2} \mathrm{O}_{3}\right)_{3}\right]$

Hence, the correct answer is option: 'B'.

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