Question

A violet colour compound is formed in detection of $ S $ in a compound

• A. $ N{{a}_{4}}[Fe{{(CN)}_{5}}NOS] $
• B. $ N{{a}_{3}}[Fe{{(CN)}_{5}}NOS] $
• C. $ N{{a}_{2}}[Fe{{(CN)}_{5}}NOS] $
• D. $ N{{a}_{2}}[Fe{{(CN)}_{5}}NO] $

Answer 1

Answer: (A)

When $ N{{a}_{2}}S $ is mixed with freshly prepared sodium nitroprusside, a deep violet colour indicates the presence of sulphur.
$ Na_2S + \underset{\text{sodium nitroprusside}}{Na_2[Fe(NO)(CN)_5]} \to $
$\underset{\text{sodium thionitro prusside violet coloured complex}}{Na_4[(Fe(CN)_5NOS]}$