Test: Properties of Alcohols - NEET MCQ

• The correct answer is option D
• Acyl chloride
• Esters are derived from carboxylic acids. A carboxylic acid contains the -COOH group, and in an ester, the hydrogen in this group is replaced by a hydrocarbon group of some kind.
• We shall just be looking at cases where it is replaced by an alkyl group, but it could equally well be an aryl group (one based on a benzene ring).
• A common ester - ethyl ethanoate
• The most commonly discussed ester is ethyl ethanoate. In this case, the hydrogen in the -COOH group has been replaced by an ethyl group.

The correct answer is Option D.

• Aryl halides are compounds where a halogen atom is directly bonded to an aromatic ring.
• When aryl halides are heated with 6-8% NaOH solution at 623 K under 300 atm, a nucleophilic substitution reaction occurs.
• This process is known as the Dow process, where the halogen is replaced by an -OH group.
• The result is the formation of phenol.
• Therefore, when an aryl halide undergoes this reaction, the product is phenol (Option A).

Carbonium ion formed in 1^st step undergoes rearrangement to give tert. carbonium ion since tert-carbonium ions are more stable than secondary one.

The reaction of ethanol with concentrated sulphuric acid at 383 K as:

Then the product formed when further heated to 443 K gives:

- Solubility in Water: Solubility of alcohols in water is largely determined by the ability to form hydrogen bonds. Methanol (CH₃OH) has a small alkyl group, which makes it highly polar and capable of forming strong hydrogen bonds with water molecules.
- Comparison:
- Methanol (CH₃OH) has the shortest carbon chain, enhancing its solubility.
- Longer carbon chains in other options (propyl, isopropyl, and phenol) make them less polar, reducing water solubility.
- Conclusion: Methanol (Option A) is the most soluble in water due to its short carbon chain and strong hydrogen bonding capability.

The correct answer is Option D.

Phenols have higher boiling point than toluene due to the presence of intermolecular hydrogen bonding in phenols. The formation of hydrogen bonds increases the intermolecular force of attraction between the phenol molecules and thereby increases its boiling point.

Isopropyl alcohol, also known as 2-propanol, undergoes oxidation to form:

• Acetone (Option A): When isopropyl alcohol is oxidized, it loses hydrogen atoms and forms acetone (propanone). The reaction involves the conversion of a secondary alcohol to a ketone.
• Other options like Ether, Acetaldehyde, and Methane are incorrect:
  
  
  • Ether is not formed from this oxidation.
  • Acetaldehyde is derived from primary alcohols, not secondary ones.
  • Methane is a simple alkane, unrelated to this reaction.
  • The reaction is as follows:
    
  
   

In the Fischer-Speier esterification, concentrated sulfuric acid (H₂SO₄) is used as the catalyst for the following reasons:

1. Protonation of Carboxyl Group: H₂SO₄ protonates the carbonyl oxygen of the carboxylic acid, increasing the electrophilicity of the carbonyl carbon, making it more reactive towards alcohol.

2. Water Removal: It acts as a dehydrating agent, absorbing the water produced in the reaction, thereby shifting the equilibrium towards ester formation according to Le Chatelier’s principle.

3. Catalytic Role: H₂SO₄ is not consumed in the reaction, only aiding the esterification process by creating an acidic environment.

Other options like dry HCl, concentrated HNO₃, and pyridine are not typically used in this reaction. HCl is more relevant in other types of reactions, HNO₃ is an oxidizing agent, and pyridine is basic, which is unsuitable for esterification requiring acidic conditions.

Therefore, concentrated sulfuric acid is the ideal catalyst in Fischer-Speier esterification.

The correct answer is option D
Zymase is an enzyme complex that catalyzes the fermentation of sugar into ethanol and carbon dioxide. It occurs naturally in yeasts. Zymase activity varies among yeast strains. Zymase is also the brand name of the drug pancrelipase.