Statement I: At the same temperature, water has higher vapour pressure than acetic acid.

Statement II: Hydrogen bonding in water is weaker than in acetic acid.

If Statement I is CORRECT, but Statement II is INCORRECT

The answer correct answer is option 3. If Statement I is CORRECT, but Statement II is INCORRECT.

Let us delve into each statement:

Statement I: At the same temperature, water has higher vapor pressure than acetic acid.

Vapor pressure is a measure of the tendency of a substance to evaporate. At a given temperature, molecules with higher vapor pressure are more likely to escape from the liquid phase and enter the gas phase. This is due to the fact that a higher vapor pressure indicates a higher concentration of molecules in the gas phase.

Water \((H_2O)\) and acetic acid \((CH_3COOH)\) have different molecular structures and intermolecular forces. Water molecules can form extensive hydrogen bonds with each other due to the highly electronegative oxygen atom. Acetic acid molecules also have hydrogen bonding capabilities but to a lesser extent due to the presence of the carboxylic acid functional group \((-COOH)\), which is less electronegative than oxygen. As a result, water molecules tend to have stronger intermolecular forces compared to acetic acid.

Due to the stronger intermolecular forces in water, more water molecules escape into the vapor phase compared to acetic acid molecules at the same temperature. Therefore, water has a higher vapor pressure than acetic acid at the same temperature.

Statement II: Hydrogen bonding in water is weaker than in acetic acid.

This statement is incorrect. Hydrogen bonding arises from the attraction between the positively charged hydrogen atom of one molecule and a highly electronegative atom (such as oxygen or nitrogen) of another molecule.

In water, hydrogen bonding is very significant. Each water molecule can form hydrogen bonds with up to four neighboring water molecules due to its bent shape and polar nature. The oxygen atom in one water molecule attracts the hydrogen atoms of neighboring water molecules, forming strong hydrogen bonds. These hydrogen bonds give water unique properties such as high surface tension, high boiling point, and high heat capacity.

Acetic acid also has hydrogen bonding capabilities due to the presence of the carboxylic acid functional group \((-COOH)\). However, the hydrogen bonding in water is typically stronger than in acetic acid because the electronegativity of the oxygen atom in water is higher than that of the oxygen atom in the carboxylic acid group of acetic acid.

Therefore, hydrogen bonding in water is generally stronger compared to acetic acid, making Statement II incorrect.

In summary, Statement I is true because water typically has a higher vapor pressure than acetic acid at the same temperature due to stronger intermolecular forces, while Statement II is false because hydrogen bonding in water is stronger compared to acetic acid.