Phenols

94 g 480 g
94 g of phenol requires = 480 g
2 g of phenol will require =
= 10.22 g

An alkyl halide on heating with dry silver oxide gives ether.

The structures of possible alcohols having formula are as Among these, 2-methylpropan-2-ol cannot be prepared by the reduction of carbonyl compounds.

Moles of
2 moles of Na will give 1 mole of hydrogen.
The molecular weight of hydrogen is .
Thus the quantity of hydrogen gas liberated is or

Step 1: Define dihydric phenol.
A dihydric phenol contains two hydroxyl ( ) groups attached to a benzene ring.
Step 2: Analyze each option.
p-Cresol has one group. Phloroglucinol and pyrogallol contain three groups.
Step 3: Identify correct compound.
Catechol contains two hydroxyl groups in the ortho position.
Step 4: Conclusion.
Therefore, catechol is a dihydric phenol.

Step 1: Structure of hydroxyquinol.
Hydroxyquinol is also known as benzene-1,2,4-triol. The term “triol” indicates the presence of three hydroxyl groups.

Step 2: Counting hydroxyl groups.
The benzene ring in hydroxyquinol contains three groups attached at different positions.

Step 3: Conclusion.
Therefore, hydroxyquinol contains three hydroxy groups.

Step 1: Understand the terms disinfectant and antiseptic.
Disinfectants are substances used to kill microorganisms on non-living surfaces, while antiseptics are used on living tissues to prevent infection.
Step 2: Analyze the given options.
Veronal is a sedative drug.
Seldane is an antihistamine drug.
Prontosil is an antibacterial drug used as a chemotherapeutic agent.
Phenol is used both as a disinfectant (on surfaces) and as an antiseptic (in dilute solutions).
Step 3: Conclusion.
Hence, phenol is used as both a disinfectant and an antiseptic.

Step 1: Recall the nature of glycolic and lactic acids.
Both glycolic acid and lactic acid are hydroxy acids capable of undergoing condensation polymerization.
Step 2: Identify the polymer formed.
When these two acids combine, they form a biodegradable polyester known as Dextron.
Step 3: Eliminate other options.
Buna–N: Copolymer of butadiene and acrylonitrile.
PHBV: Formed from hydroxybutanoic acids.
Nylon–2–nylon–6: Polyamide formed from amino acids.
Step 4: Conclusion.
The correct polymer formed is Dextron.

Step 1: Define dihydric phenols.
Dihydric phenols are aromatic compounds containing two hydroxyl ( ) groups attached to a benzene ring.
Step 2: Analyze each option.
(A) Quinol: It contains two hydroxyl groups in para position and is a dihydric phenol.
(B) Catechol: It contains two hydroxyl groups in ortho position and is a dihydric phenol.
(C) Phloroglucinol: It contains three hydroxyl groups and is a trihydric phenol, not dihydric.
(D) Resorcinol: It contains two hydroxyl groups in meta position and is a dihydric phenol.
Step 3: Conclusion.
Phloroglucinol is not a dihydric phenol because it contains three hydroxyl groups.

Step 1: Understanding isotonic solutions.
Isotonic solutions have the same osmotic pressure. The osmotic pressure is affected by the number of particles in solution. Thus, the solution with the highest number of ions per mole will deviate from being isotonic.

Step 2: Analyzing the options.
(A) B: This solution contains 2 ions per formula unit (NaCl).
(B) A: Urea does not dissociate, so it contributes 1 particle per molecule.
(C) D: AlCl₃ dissociates into 4 ions per formula unit, making it the most concentrated in terms of particles. Therefore, it is not isotonic.
(D) C: BaCl₂ dissociates into 3 ions per formula unit.

Step 3: Conclusion.
The correct answer is (C) D, as AlCl₃ gives the most ions, affecting the osmotic pressure.

Step 1: Understanding the Reaction.
Carbolic acid (phenol) reacts with concentrated nitric acid in the presence of concentrated sulfuric acid. This is a nitration reaction, where the nitronium ion (NO ) is generated in the presence of sulfuric acid, and phenol undergoes electrophilic aromatic substitution to form picric acid (2,4,6-trinitrophenol). The reaction introduces three nitro groups (-NO ) at positions 2, 4, and 6 of the benzene ring.

Step 2: Analyzing the options.
(A) Benzoic acid: Incorrect. Benzoic acid is not formed in this reaction; it would be formed by oxidizing toluene.
(B) Picric acid: Correct. Picric acid is the product formed by the nitration of phenol with concentrated nitric acid and sulfuric acid.
(C) Phthalic acid: Incorrect. Phthalic acid is formed by the oxidation of naphthalene, not by nitration of phenol.
(D) Benzene sulphonic acid: Incorrect. This is the product of sulfonation of benzene with sulfuric acid, not nitration.

Step 3: Conclusion.
The correct product formed is Picric acid, corresponding to option (B).

Step 1: Understanding the toxicity of substances.
- Phosgene is highly toxic and was used as a chemical weapon. - Gaseous chlorine is toxic and can cause severe damage to the respiratory system. - Phosphine is highly toxic and can be lethal in even small amounts. - Red phosphorus is relatively less toxic and is used safely in matches and other applications.

Step 2: Conclusion.
The correct answer is (D) Red phosphorus, as it is non-poisonous compared to the other options.

Step 1: Use the formula for molarity.
The formula for molarity is: First, calculate the moles of NaOH:
Step 2: Convert volume to dm .
The volume is 250 cm , which is equal to:
Step 3: Calculate molarity.

Step 4: Conclusion.
The molarity of the solution is 0.32 mol dm .

Step 1: Understanding the Reimer-Tiemann reaction.
The Reimer-Tiemann reaction involves the reaction of phenol with chloroform (CHCl ) in the presence of sodium hydroxide (NaOH) to form salicylaldehyde (o-hydroxybenzaldehyde). This reaction is used to introduce an aldehyde group (-CHO) into the ortho position of a phenol ring.
Step 2: Analyzing the options.
(A) Reimer - Tiemann reaction: This is the correct answer. The reaction between phenol, chloroform, and NaOH is known as the Reimer-Tiemann reaction.
(B) Friedel craft’s reaction: This involves alkylation or acylation of an aromatic compound using a Lewis acid catalyst, not the same as the Reimer-Tiemann reaction.
(C) Stephens reaction: This is incorrect. The Stephens reaction involves the reduction of nitriles, not phenols.
(D) Kolbe’s reaction: This involves the decarboxylation of phenol, not its reaction with chloroform.
Step 3: Conclusion.
The correct answer is (A) Reimer - Tiemann reaction.

Step 1: Understanding the electrophilic substitution of phenol.
When phenol reacts with dilute nitric acid, the nitronium ion (NO ) attacks the phenol ring, and the product formed depends on the position of the substituent on the ring. At room temperature and with dilute nitric acid, the nitro group typically substitutes at the meta position due to the electron-donating nature of the hydroxyl group.
Step 2: Analyzing the options.
(A) p-nitrophenol: This is not the major product as the nitro group generally enters the meta position in dilute nitric acid.
(B) m-nitrophenol: This is correct. The major product is m-nitrophenol, formed by electrophilic substitution at the meta position.
(C) 2,4,6-trinitrophenol: This product is formed under more concentrated nitric acid conditions, not dilute.
(D) o-nitrophenol: This is incorrect as the nitro group does not preferentially enter the ortho position in this reaction.
Step 3: Conclusion.
The correct answer is (B) m-nitrophenol.

Step 1: Understanding the phenol.
2, 5-dichlorophenol is isolated from the defensive secretion of certain grasshopper species. It is a defensive chemical that helps to protect the grasshopper from predators.

Step 2: Analyzing the options.
(A) 4-Methylphenol: This is not the correct phenol isolated from grasshopper secretion.
(B) Benzene-1, 3-diol: Incorrect — This is a different compound.
(C) 2, 5-dichlorophenol: Correct — This is the correct phenol isolated from grasshopper secretion.
(D) Phenol: Incorrect — This is a simple phenol, not the one isolated in this case.

Step 3: Conclusion.
The correct answer is (C) 2, 5-dichlorophenol, as it is isolated from the defensive secretion of grasshoppers.

Phenols exhibit greater acidity compared to alcohols due to the resonance stabilization of the phenoxide ion formed after losing a proton ( ). This resonance delocalizes the negative charge on the oxygen, enhancing the compound's acidity. Electron-withdrawing substituents, such as -Cl, further increase the acidity of phenols by stabilizing the negative charge on the oxygen atom. Step 1: Structure comparison.
Benzyl alcohol: Less acidic, as the hydroxyl group is attached to a saturated carbon, and there is no resonance stabilization.
Cyclohexanol: Similar to benzyl alcohol, it lacks resonance stabilization and is therefore less acidic.
Phenol: More acidic due to the resonance stabilization of the phenoxide ion.
m-Chlorophenol: The most acidic, as the -Cl group is an electron-withdrawing group, which enhances resonance stabilization and increases acidity.
Final Answer:

Step 1: Concept
Haloalkynes are organic compounds where a halogen atom is directly attached to a carbon atom involved in a triple bond ( ).
Step 2: Analysis
In an alkyne, the carbon atoms involved in the triple bond are hybridized. Therefore, in a haloalkyne, the halogen is bonded to an carbon.
Step 3: Comparison
- Option (B) describes haloalkenes (vinylic). - Option (C) describes allylic halides. - Option (D) describes haloarenes (aryl halides).
Final Answer: (A)

Step 1: Concept
Dihydroxy derivatives of benzene have specific common names based on the relative positions of the groups.
Step 2: Identification
- 1,2-diol: Catechol - 1,3-diol: Resorcinol - 1,4-diol: Quinol (or Hydroquinone)
Step 3: Conclusion
Benzene-1,4-diol is commonly known as Quinol.
Final Answer: (C)

Concept: Phenol contains an group attached to the benzene ring. The group is:

• Electron donating
• Strongly activating
• Ortho and para directing

Thus, electrophilic substitution occurs readily at the ortho and para positions.
Step 1: {Reaction with bromine water.} When phenol reacts with bromine water:
Step 2: {Substitution positions.} Because phenol strongly activates the ring, bromination occurs at:
Step 3: {Major product.} The product formed is: This compound forms as a white precipitate in bromine water.