Carboxylic Acids

Step 1: Explanation.
Formic acid (HCOOH) is unique because it contains both the –CHO (aldehyde group) and the –COOH (carboxylic acid group). Hence, it exhibits the properties of both aldehydes and acids.
Step 2: Aldehydic nature.
Formic acid gives reactions typical of aldehydes such as:
- (i) Reducing nature: It reduces Tollen’s reagent and Fehling’s solution.
Step 3: Acidic nature.
Formic acid also behaves as a typical carboxylic acid:
- It reacts with metals to liberate hydrogen gas.
- It neutralizes alkalis to form formates.
Step 4: Conclusion.
Thus, due to the presence of both aldehyde and acid functional groups, formic acid exhibits dual behavior — reducing like an aldehyde and acidic like a carboxylic acid.

Step 1: Definition of Methanoic Acid.
Methanoic acid, also known as formic acid (HCOOH), is the simplest carboxylic acid. It has a single carbon atom in its structure and is commonly found in ants and other insects.
Step 2: Definition of Ethanoic Acid.
Ethanoic acid, also known as acetic acid (CH₃COOH), is a carboxylic acid that contains two carbon atoms. It is the main component of vinegar, besides water.
Step 3: Key Differences.
- Molecular Formula: - Methanoic acid: - Ethanoic acid: - Number of Carbon Atoms: - Methanoic acid has 1 carbon atom. - Ethanoic acid has 2 carbon atoms. - Occurrence: - Methanoic acid is found in ants and some plants. - Ethanoic acid is found in vinegar and is used in food processing. - Acidity: - Both are weak acids, but methanoic acid is slightly stronger than ethanoic acid due to its simpler structure.
Final Answer: Methanoic acid has one carbon atom and is found in ants, while ethanoic acid has two carbon atoms and is found in vinegar.
Final Answer:

Step 1: Understand Aldol condensation.
Aldol condensation is a reaction in which an enolate ion of an aldehyde or ketone reacts with another aldehyde or ketone molecule to form a β-hydroxy aldehyde or ketone, which then undergoes dehydration to give an α,β-unsaturated carbonyl compound.
Step 2: Identify the compounds capable of Aldol condensation.
- CCl CHO (Option A) is a chloro-aldehyde, which does not participate in Aldol condensation. - CH -C-CHO (Option B) is an aldehyde with a hydrogen atom adjacent to the carbonyl group, making it suitable for Aldol condensation. - CH CHO (Option C) is acetaldehyde, but it is too simple for the reaction to take place effectively in this context. - HCHO (Option D) is formaldehyde, which is not typically used in Aldol condensation reactions.
Step 3: Apply to the options.
The correct compound for Aldol condensation is (B) CH -C-CHO.
Final Answer:

Step 1: Understand vinegar composition.
Vinegar is a dilute solution of acetic acid (CH COOH) in water. The concentration of acetic acid in vinegar typically ranges from 6% to 10%.
Step 2: Analyze the options.
- 10-20% acetic acid (Option A) is too concentrated for vinegar. - 10% acetic acid (Option B) is a common concentration, but the typical concentration range for vinegar is slightly lower. - 6-10% acetic acid (Option C) is the correct range for typical vinegar concentration. - 100% acetic acid (Option D) is pure acetic acid, which is not the composition of vinegar.
Step 3: Apply to the options.
The correct concentration of acetic acid in vinegar is 6-10%, so the correct answer is (C).
Final Answer: