Assertion : ${N H}_{2} - {N H}_{2}$ gives Prussian blue colour during Lassaigne test (element detection test). Reason: NaCN gives Prussian blue colour of ${F e}_{4} {[F e ({C N}_{6})]}_{3}$ with $F e {S o}_{4}, F e {C I}_{3}$ .

Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

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Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion

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Assertion is correct but Reason is incorrect

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Assertion is incorrect and Reason is correct

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Solution

The correct option is D Assertion is incorrect and Reason is correct

The carbon and Nitrogen present in the organic compound with fusion with sodium metal gives sodium cyanide.
$N a + C + N ⟶ N a C N$
which on further reaction with $F e S O_{4}$ or $F e C I_{3}$ from prussian blue colour solution of Ferric Ferro cyanide.
$6 N a C N + F e S O_{4} ⟶ N a_{4} [F e (C N)_{6}] S o d i u m F e r r o c y a n i d e + N a_{2} S O_{4}$
$N a_{4} [F e (C N)_{6}] + F e^{+ 3} ⟶ F e_{4} [F e (C N)_{6}]_{3} F e r r i c F e r r o c y a n i d e$ (prussian blue in colour)
Hence, result is correct.
$N H_{2} - N H_{2}$ do not give Prussian blue colour in Lassaigne test as there is Carbon needed for Lassaigne test for formation of $N a C N$ . But in hydrazine no carbon is present. Therefore, assertion is incorrect.

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