The relative acidity of the molecules can be determined by comparing their acid dissociation constants Ka or pKa values. The lower the pKa value, the stronger the acid. Here are the pKa values for the given molecules:1. Acetic acid CH3COOH : pKa 4.762. Ethanol CH3CH2OH : pKa 15.93. Water H2O : pKa 15.7Based on these values, the relative acidity of the molecules is as follows:Acetic acid > Water > EthanolExplanation:1. Acetic acid CH3COOH is the most acidic among the three molecules due to the presence of the carboxylic acid functional group COOH . When acetic acid donates a proton H+ , it forms the acetate ion CH3COO- which is resonance-stabilized. This stabilization of the conjugate base makes it easier for acetic acid to donate a proton, making it a stronger acid compared to water and ethanol.2. Water H2O is more acidic than ethanol but less acidic than acetic acid. Water can act as both an acid and a base amphoteric . When it donates a proton, it forms the hydroxide ion OH- . The oxygen atom in water has two lone pairs of electrons, which can stabilize the negative charge on the hydroxide ion to some extent.3. Ethanol CH3CH2OH is the least acidic among the three molecules. The hydroxyl group OH in ethanol is not as acidic as the carboxylic acid group in acetic acid or the oxygen atom in water. When ethanol donates a proton, it forms the ethoxide ion CH3CH2O- , which is not stabilized by resonance or any other significant stabilizing factor. As a result, ethanol is less likely to donate a proton and is a weaker acid compared to acetic acid and water.