Relative Strength of Organic Acids

(i) A compound is acidic in nature, if its conjugate base can stabilize through  resonance. Thus phenol is acidic while ethanol is neutral because the conjugate base of phenol  can be stabilized through resonance while that of alcohol  can not.

(ii) Hydrogen atom attached to sp-hybridized carbon is more acidic than that on  hybridized carbon which in turn is more acidic than that on  hybridized carbon.

Thus,