Organic Reactions

Step 1: Analyzing the reaction.
The given reaction involves the reduction of a nitro group (NO ) to form an amine group (NO to NH ) and an alkene group (CH=CH) undergoing hydration. This is a typical reaction for the reduction of nitro compounds and hydration of alkenes. The reagent H O (aqueous acid) facilitates both processes: it reduces the nitro group and promotes hydration.
Step 2: Analyzing the options.
(A) K Cr O : Potassium dichromate is an oxidizing agent, not a reducing agent, so it is not involved in this reaction.
(B) KMnO : Potassium permanganate is an oxidizing agent, so it is not suitable for this reduction reaction.
(C) H O : This is the correct answer. Aqueous acid is commonly used to reduce nitro groups to amines and to hydrate alkenes.
(D) LiAlH : Lithium aluminium hydride is a strong reducing agent, but it would not be used here for hydration.
Step 3: Conclusion.
The correct answer is (C) H O .

Step 1: Relation for FCC lattice.
In a face centred cubic (fcc) structure, atoms touch along the face diagonal. The relation between edge length and atomic radius is:


Step 2: Substituting given value.


Step 3: Calculation.


Step 4: Conclusion.
Thus, the edge length of the unit cell of aluminium is 353.5 pm.

Step 1: Analyze the first reaction.
In the first step, compound reacts with thionyl chloride in the presence of pyridine under reflux conditions. This reaction converts an alcohol into the corresponding alkyl chloride. Hence, compound must be an alcohol.
Step 2: Analyze the second reaction.
The alkyl chloride reacts with alcoholic potassium cyanide on heating. In this reaction, the cyanide ion replaces the halide ion via nucleophilic substitution, forming a nitrile. The product formed is propane nitrile, which contains three carbon atoms.
Step 3: Carbon chain analysis.
Since the nitrile product has three carbon atoms, the alkyl halide must be chloroethane, which upon reaction with KCN gives propionitrile (propane nitrile). Therefore, the original alcohol must be ethanol.
Step 4: Evaluation of options.
(A) Ethanol: Correct, as it forms chloroethane with , which then gives propane nitrile with KCN.
(B) Propane: Incorrect, as alkanes do not react with .
(C) 1-Chloropropane: Incorrect, as it is already a halide and not the starting compound .
(D) Propan-1-ol: Incorrect, as it would lead to butane nitrile, not propane nitrile.
Step 5: Conclusion.
Thus, the compound is correctly identified as ethanol.

Step 1: Analyzing the reaction.
The given reaction involves the nitration of an aromatic compound, followed by reduction. The nitration reaction involves the use of a mixture of nitric acid (HNO ) and hydrochloric acid (HCl), followed by heating at 273K. The reduction step is done with water and dilute H SO . This combination of reactions leads to the formation of an amine group, specifically aniline (C H NH ).
Step 2: Analyzing the options.
(A) Benzene: This is incorrect as the reaction produces an amine, not just benzene.
(B) Chlorobenzene: This is incorrect because the reaction does not produce chlorobenzene.
(C) Aniline: This is the correct answer, as the product of the reaction is aniline (C H NH ).
(D) Cumene: This is incorrect because the reaction does not involve cumene.
Step 3: Conclusion.
The correct answer is (C) Aniline.

Step 1: Understanding the process.
Sodium hydroxide (NaOH) is commonly used in the manufacture of soft soap. The reaction involves the saponification of fats and oils with sodium hydroxide, producing soap and glycerol.
Step 2: Analyzing the options.
(A) Lithium: Incorrect. Lithium hydroxide is not commonly used in soap making.
(B) Caesium: Incorrect. Caesium hydroxide is highly reactive and not used in soap making.
(C) Potassium: Incorrect. Potassium hydroxide is used in soft soap, but sodium is more common.
(D) Sodium: Correct. Sodium hydroxide is the most common alkali used to make soft soap.
Step 3: Conclusion.
The correct answer is (D) Sodium, as sodium hydroxide is widely used in the production of soft soap.

Step 1: Understanding Kolbe's reaction.
Kolbe’s reaction is a decarboxylation reaction of carboxylates in the presence of a strong base, followed by the addition of carbon dioxide. The reaction given in the question represents the Kolbe reaction, which leads to the formation of a carboxylic acid.
Step 2: Analyzing the options.
(A) Kolbe's reaction: Correct — This is the correct reaction, where sodium phenoxide reacts with carbon dioxide to form salicylic acid.
(B) Sandmeyer's reaction: Incorrect. This involves the conversion of diazonium salts to aryl halides, not a decarboxylation.
(C) Reimer-Tiemann reaction: Incorrect. This reaction involves the introduction of a formyl group to a phenol molecule.
(D) Stephen reaction: Incorrect. This reaction is related to the formation of imines, not a decarboxylation.
Step 3: Conclusion.
The correct answer is (A) Kolbe's reaction, which is a decarboxylation reaction that leads to the formation of a carboxylic acid.

Concept:
The cyanide ion is an ambident nucleophile, meaning it has two possible sites of attack:

• Carbon end
• Nitrogen end

The type of reagent used determines which atom participates in the nucleophilic attack, thereby deciding the final product.
Step 1: {Reaction with .} is an ionic compound and dissociates completely in solution to give free ions. The nucleophilic attack occurs through the carbon atom, forming a bond and producing alkyl cyanides (nitriles).
Step 2: {Reaction with .} is largely covalent in nature. In this compound, the carbon atom is strongly bonded to silver, leaving the nitrogen atom available for nucleophilic attack. As a result, the reaction forms alkyl isocyanides.
Step 3: {Conclusion.} Since the formation of alkyl isocyanides occurs when nucleophilic attack takes place through nitrogen, the reagent required is:

Concept: Alkyl halides react differently with depending on the solvent:

• Aqueous → Substitution reaction producing alcohol.
• Alcoholic → Elimination reaction producing an alkene.

Alcoholic promotes dehydrohalogenation, where a hydrogen atom and a halogen atom are removed from adjacent carbon atoms, forming a double bond.
Step 1: {Identify the reactant.} The given compound is which is ethyl bromide, a primary alkyl halide.
Step 2: {Apply elimination with alcoholic .} In the presence of alcoholic , the reaction proceeds via elimination of:

• from one carbon
• from the adjacent carbon

Step 3: {Identify the product.} The elimination forms the alkene which is ethene.

Concept: Ketones react with hydrazine in a condensation reaction to form hydrazones. This reaction involves nucleophilic attack of hydrazine on the carbonyl carbon followed by elimination of water. General reaction: The product is called a hydrazone.
Step 1: {Identify the functional group in ketones.} Ketones contain the carbonyl group:
Step 2: {Reaction with hydrazine.} Hydrazine acts as a nucleophile and attacks the carbonyl carbon, forming an intermediate which eliminates water.
Step 3: {Formation of final product.} The final product contains the functional group which is known as a hydrazone. Hence, the correct option is (B).