JEE Main · 2024 · 29 Jan 2024 · Shift 1 · Practical and Analytical Chemistry

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Appearance of blood red colour, on treatment of the sodium fusion extract of an organic compound with FeSO₄ in presence of concentrated H₂SO₄ indicates the presence of element/s

(A)Br
(B)N
(C)N and S✓ Correct
(D)S

Answer: (C)

Solution

When the sodium fusion extract contains both nitrogen and sulphur, fusion generates

NaSCN

. Treating this with

FeSO_{4}

and conc.

H_{2} SO_{4}

(which oxidises some

Fe^{2 +}

Fe^{3 +}

) gives the blood-red complex

[Fe(SCN)]^{2 +}

.

This colour therefore confirms the presence of both nitrogen and sulphur together.

Key confirmed: C (N and S).

JEE Main · 2024 · 29 Jan 2024 · Shift 1 · Single correct option

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