WBJEE 2021 Physics and Chemistry Solved Paper

Acetic acid is most acidic as its conjugte base has equivalent Resonating structure followed by para-nitrophenol. Ethanol is less acidic then para-nitrophenol as conjugate base of p-nitrophenol is resonance stablized but not ethoxide (CH3−CH2−O) Also electronegativity of carbon is lesser than oxygen, hence acetylene is less acidic.