Relative acidic strength of alcohol, phenol, water and carboxylic acid is:

Explanation

The acidity of a molecule depends on the stability of its ions after releasing the H+, the more stable the negative ion is the more acidic a molecule is. The acidity of a carboxylic acid is higher than alcohols and phenols. Because of the carboxylate ion, the conjugate base of a carboxylic acid is stabilized by two equivalent resonance structures in which the negative charge is effectively delocalized between two more electronegative oxygen atoms. For phenols, the phenoxide ion obtained after the removal of a proton is stabilized by resonance (in the benzene ring) whereas the alcohol ion obtained after the removal of a proton from alcohols is destabilized by the +I Effect of the alkyl group attached. Therefore, phenol is a stronger acid than alcohols, On the other hand, alcohol is a weaker acid than water because electron releasing alkyl group in alcohol increases the electron density of oxygen, and hence the polarity of the O−H bond in ethanol decreases which results in the decreasing acidic strength, Hence, acidic strength increases in the order given above.