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NEET · Chemistry · STD 11 - 8.3. Organic chemistry purification and characterization

Nitrogen detection in an organic compound is carried out by Lassaigne's test. The blue colour formed corresponds to which of the following formulae ?

A \(Fe_3[Fe(CN)_6]_2\)
B \(Fe_4[Fe(CN)_6]_3\)
C \(Fe_4[Fe(CN)_6]_2\)
D \(Fe_3[Fe(CN)_6]_3\)

Verified Solution

Answer & Solution

Correct Answer

(B) \(Fe_4[Fe(CN)_6]_3\)

Step-by-step Solution

Detailed explanation

\(N a+C+N\stackrel{\Delta}{\rightarrow} N a C N\) \(2 \mathrm{NaCN}+\mathrm{FeSO}_{4} \longrightarrow \mathrm{Fe}(\mathrm{CN})_{2}+\mathrm{Na}_{2} \mathrm{SO}_{4}\)

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

Same subject

Match List I with List II :

List-I (Transition metal/compound/complex)	List-II (Catalytic Role)
(A) \(V _2 O _5\)	(I) Preparation of ammonia from \(N _2 / H _2\) mixture
(B) Fe	(II) Polymerisation of alkynes
(C) \(PdCl _2\)	(III) Preparation of \(H _2 SO _4\) from \(SO _2\)
(D) Ni complex	(IV) Oxidation of ethyne to ethanal

Choose the correct answer from the options given below:

NEET 2026 Hard

Match the following aspects with the respective metal.

Aspects	Metal
\((a)\) The metal which reveals a maximum number of oxidation states	\((i)\) Scandium
\((b)\) The metal although placed in \(3 d\) block is considered not as a transition element	\((ii)\) Copper
\((c)\) The metal which does not exhibit variable oxidation states	\((iii)\) Manganese
\((d)\) The metal which in \(+1\) oxidation state in aqueous solution undergoes disproportionation	\((iv)\) Zinc

Select the correct option

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Match List \(I\) with List \(II\).

List \(I\) (Interacting species)	List \(II\) (Name of interaction)
\(A\). A Leopard and a Lion in a forest/grassland	\(I\). Competition
\(B\). A Cuckoo laying egg in a Crow's nest	\(II\). Brood parasitism
\(C\). Fungi and root of a higher plant in Mycorrhizae	\(III\). Mutualism
\(D\). A cattle egret and a Cattle in a field	\(IV\). Commensalism

Choose the correct answer from the options given below.

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