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Some Basic Concepts of Organic Chemistry question

2023 · Q99
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Some Basic Concepts of Organic Chemistry question

2023 · Q99

NEETChemistrySome Basic Concepts of Organic ChemistryMCQ+4 / −1

In Lassaigne's extract of an organic compound, both nitrogen and sulphur are present, which gives blood red colour with Fe3+\mathrm{Fe}^{3+}Fe3+ due to the formation of-

  1. A
    NaSCN
  2. B
    [Fe(CN)5NOS]4−\left[\mathrm{Fe}(\mathrm{CN})_{5} \mathrm{NOS}\right]^{4-}[Fe(CN)5​NOS]4−
  3. C
    [Fe(SCN)]2+[\mathrm{Fe}(\mathrm{SCN})]^{2+}[Fe(SCN)]2+
  4. D
    Fe4[Fe(CN6)]3⋅xH2O\mathrm{Fe}_{4}\left[\mathrm{Fe}\left(\mathrm{CN}_{6}\right)\right]_{3} \cdot \mathrm{xH}_{2} \mathrm{O}Fe4​[Fe(CN6​)]3​⋅xH2​O
View written solutionFree

Correct answer: C

Sol. In case nitrogen and sulphur both are present in an organic compound, sodium thiocyanate is formed, it give blood red colour and no prussian blue since there are no free cyanide Ions

$$\mathrm{Na}+\mathrm{C}+\mathrm{N}+\mathrm{S} \rightarrow \mathrm{NaSCN}$$

$$\mathrm{Fe}^{+3}+\mathrm{SCN}^{\ominus} \longrightarrow[\mathrm{Fe}(\mathrm{SCN})]^{2+}$$ Blood red

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