Incorrect statement with respect to physical properties of carboxylic acids is

Options

A. Carboxylic acids have higher boiling point than alcohols of comparable molecular masses
B. Most carboxylic acids exist as dimer in the vapour phase
C. Solubility of carboxylic acids in water increases with increasing number of carbon atoms
D. Carboxylic acids are also soluble in less polar organic solvents like benzene, ether, chloroform etc.

Answer

To solve the question regarding the incorrect statement with respect to the physical properties of carboxylic acids, we will analyze the statements provided.

**Step 1: Analyze the first statement**
- **Statement:** Carboxylic acids have higher boiling points than alcohols of comparable molecular weight.
- **Analysis:** This statement is true. Carboxylic acids have higher boiling points than alcohols due to the presence of hydrogen bonding between carboxylic acid molecules, which is stronger than the hydrogen bonding in alcohols.

**Step 2: Analyze the second statement**
- **Statement:** Most carboxylic acids exist as dimers in the vapor phase.
- **Analysis:** This statement is also true. Carboxylic acids can form dimers through hydrogen bonding, particularly in the vapor phase, which contributes to their higher boiling points.

**Step 3: Analyze the third statement**
- **Statement:** Solubility of carboxylic acids in water increases with increasing number of carbon atoms.
- **Analysis:** This statement is incorrect. As the number of carbon atoms in a carboxylic acid increases, the solubility in water generally decreases due to the increasing hydrophobic character of the longer carbon chains, which outweighs the hydrophilic carboxyl group.

**Step 4: Analyze the fourth statement**
- **Statement:** Carboxylic acids are soluble in less polar organic solvents like benzene, ethyl acetate, and chloroform (CHCl3).
- **Analysis:** This statement is true. Carboxylic acids can dissolve in less polar organic solvents due to their ability to engage in dipole-dipole interactions and hydrogen bonding with the solvent molecules.

**Conclusion:**
- The incorrect statement regarding the physical properties of carboxylic acids is the third statement: "Solubility of carboxylic acids in water increases with increasing number of carbon atoms."