Question

Which of the following structure of carboxylic acid accounts for the acidic nature
A. R—COOH
B. R—C—(OH)₂
C. R—CHO
D. None of these

Answer 1

Hint: Organic compounds are those compounds that contain carbon-carbon or carbon-hydrogen bonds. Due to the catenation property of carbon, it can form long chains of compounds containing carbon and these compounds are organic compounds.

Complete Step by Step Answer:
The organic compounds are classified on the basis of the carbon chain open-chain and closed-chain compounds and aromatic compounds. Organic compounds are also classified on the basis of the functional group attached to the carbon chain for example:
Alkene if there is a double bond between the carbon-carbon bond C=C
Alcohol if the functional group is —HO
Halides if the functional group is —X (Where X can be F, Cl, Br, I)
Aldehyde if the functional group is —CHO
Ketone if the functional group is —CO—
These are some functional groups and classes of organic compounds.
R—C—(OH)2 is diol because it contains two alcoholic groups ‘ol’ is used as a suffix for the alcoholic group (—OH) hence R—C—(OH)2 is a diol example of diols-
1. Methanediol or methylene glycol


2. Ethanediol or ethylene glycol

3. Cyclohexane-1,2-diol

R—CHO is an aldehydic group, it is also known as the carbonyl group as it contains the C=O group. Examples of aldehydes are-
1. Methanal or Formaldehyde

2. Ethanal or Acetaldehyde
3. Benzenecarbaldehyde or benzaldehyde

R—COOH is a carboxylic acid group, it is acidic in nature because on dissociation it gives R—COO^- and H⁺ ions in the solution:
Examples of carboxylic acid:
1. Ethanoic Acid or Acetic acid

2. Methanoic Acid or Formic acid

3. Oxalic Acid

4. Salicylic Acid

Hence we know that the carboxylic group is R—COOH.
Thus, Option (A) is correct

Note: Most of the Carboxylic acid occurs naturally for example in insects like ants formic acid is found, caprylic acid in coconuts, and oxalic acid in oxalis. Carboxylic acids are weak acids compared to inorganic acids like HCl, H₂SO₄, HNO₃, etc.