Which of the following reaction/s will not give aminoazobenzene?
1
only
2
only
3
only
4
and
Official Solution
Correct Option: (2)
To determine which reactions will not give aminoazobenzene, let's analyze each option:
Option A:
The starting compound is nitrobenzene.
Step (i) reduces nitrobenzene to aniline using
.
Step (ii) forms a diazonium salt with .
Step (iii) involves coupling with aniline, forming aminoazobenzene.
Option B:
The starting compound is nitrobenzene.
Step (i) attempts reduction using , which does not reduce nitrobenzene effectively to form aniline.
Because the reduction is ineffective, further steps are rendered irrelevant for forming aminoazobenzene.
Option C:
The starting compound is aniline.
Step (i) forms a diazonium salt with .
Step (ii) involves coupling with aniline, forming aminoazobenzene.
Based on the analysis, only Option B will not give aminoazobenzene.
02
PYQ 2026
medium
chemistryID: jee-main
Consider the following reactions. Total number of electrons in the -bonds and lone pair of electrons in the product (X) is :}
1
2
3
4
Official Solution
Correct Option: (2)
Concept:
The given compound is glucose. The sequence of reactions leads to formation of benzoylated aromatic derivative. Step 1: {Treatment with } Glucose on heating with HI forms -hexane. Step 2: {Oxidation over } Benzene is formed. Step 3: {Friedel–Crafts acylation} Product is benzophenone. Step 4: {Count -electrons and lone pairs} Benzophenone contains:
Two benzene rings electrons
One carbonyl group electrons
Total -electrons: Oxygen atom has two lone pairs: Total electrons in -bonds and lone pairs: Considering resonance structure contribution counted in the problem convention, the accepted answer is:
03
PYQ 2026
medium
chemistryID: jee-main
The incorrect statement from the following with respect to carbohydrates is:
1
All monosaccharides are reducing sugars.
2
The monosaccharide units obtained from hydrolysis of oligosaccharides are always the same.
3
Starch and cellulose are typical examples of polysaccharides, which are very high molecular weight compounds of more than ten monosaccharide units.
4
Open chain and cyclic structures co-exist at equilibrium that are responsible for certain properties as in the case of D-(+)-glucose.
Official Solution
Correct Option: (2)
Step 1: Understanding the Concept:
Carbohydrates are classified based on the number of sugar units they produce upon hydrolysis. Step 2: Detailed Explanation: (a): All monosaccharides (e.g., glucose, fructose) reduce Tollen’s and Fehling’s reagents. (Correct) (b): Oligosaccharides (2–10 units) can yield different sugars. For example, sucrose (an oligosaccharide/disaccharide) yields glucose and fructose. They are not always the same. (Incorrect) (c): Polysaccharides consist of a large number of monosaccharide units. (Correct) (d): Glucose exists as an equilibrium mixture of open-chain and cyclic forms. (Correct) Step 3: Final Answer:
Statement (B) is incorrect.
