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Chemistry · PYQ NEET UG 2023
हिन्दीIn Lassaigne's extract of an organic compound, both nitrogen and sulphur are present, which gives blood red colour with \( \mathrm{Fe}^{3+} \) due to the formation of -\n(1) \( \mathrm{Fe}_{4}[\mathrm{Fe}(\mathrm{CN})_{6}]_{3} \cdot \mathrm{xH}_{2} \mathrm{O} \)\n(2) \( \mathrm{NaSCN} \)\n(3) \( [\mathrm{Fe}(\mathrm{CN})_{5} \mathrm{NOS}]^{4-} \)\n(4) \( [\mathrm{Fe}(\mathrm{SCN})]^{2+} \)
Correct answer · Option 1
\( [\mathrm{Fe}(\mathrm{SCN})]^{2+} \)
Explanation
When both N and S are present, sodium thiocyanate (NaSCN) is formed in Lassaigne's test, which reacts with \( \mathrm{Fe}^{3+} \) ions to give blood-red colored \( [\mathrm{Fe}(\mathrm{SCN})]^{2+} \).
