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If an adding of $FeC{l_3}$ solution to acidified Lassaigne’s solution, a red coloration is produced, it indicates the presence of:
A) $S$
B) $N$
C) $N$ and $S$
D) $S$ and $Cl$

Answer
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Hint: We realize that the Lassaigne test is the subjective examination that is accomplished for the distinguishing proof of nitrogen, halogen, and sulfur in a natural compound. It is additionally called a sodium fusion test.

Complete step by step answer:
We must remember that the Halogens, nitrogen and sulfur are covalently attached to the natural mixes. To identify them, the components should be changed over into their ionic structures. This is finished by combining the natural compound with sodium metal. The ionic mixes framed during the combination are separated in watery arrangement and can be distinguished by straightforward substance tests. The concentrate is called sodium combination concentrate or Lassaigne's concentrate. At the point when a natural compound is warmed firmly with sodium, any halogens, nitrogen, and sulfur will be changed over into inorganic sodium salts.
Let us discuss the principle of the Lassaigne test:
The rule behind the sodium combination test is the change of the introduced component into its ionic structure by the sodium metal.
The change of nitrogen component to its ionic structure by sodium is,
${\text{Na + C + N}} \to {\text{NaCN}}$$Na + C + N \to NCN$
The change of Sulfur component its ionic structure by sodium is, $2Na + S \to N{a_2}S$
The change of halogen component its ionic structure by sodium is, $Na + X \to NaX$
In this test, The red tone is because of the generation \[Fe{\left( {CNS} \right)_3}\] complex which demonstrates the presence of both Nitrogen and Sulfur and the concentrate utilized will be $NaCNS$.
\[FeC{l_3} + 3NaCNS \to Fe{\left( {CNS} \right)_3} + 3NaCl\]
Hence option C is correct.

Note:
-Presently we see the technique to complete the Lassaigne test:
-Gently heat the little bit of sodium metal in a combination cylinder and soften the metal till it frames a sparkling globule.
-After softening, add a given substance and warmth emphatically and squash the scorching cylinder in refined water taken in a china dish.
-Boiled the substance at that point cool and channel. The filtrate is known as Lassaigne's concentrate.
-Divide the concentrate and play out the individual test for the components.