Phenol is less acidic than  

I. Ethanol

II. o-nitrophenol 

III. o-methylphenol

IV. o-methoxyphenol 

<p><span data-teams="true">This is a multiple choice answer as classified in NCERT Exemplar</span></p><p> (IV) <em>o-</em>methoxy phenol</p><p>The stability of the conjugate base&nbsp; determines the acidic character of the compound.&nbsp; Higher the stability of the conjugate base, the higher is the acidic character.</p><p>Phenol, O-nitrophenol, O-methyl phenol, and O-methoxy phenol all are aromatic compounds. In aromatic compounds, the negative charge of the conjugate base charge is delocalised. The delocalisation of negative charge gives additional stability to the compound.&nbsp;</p><p>Ethanol is not aromatic and it cannot delocalise the negative charge formed after the&nbsp; H⁺ ion leaves the c. So, it is the least acidic among the given options. Thus, we can eliminate it.</p><p>There are two types of groups, the electron-withdrawing, and the electron releasing group. The methyl group and the methoxy group are electron releasing groups. They release the electrons and hence decreases the stability of the negatively charged conjugate base.</p><p>On the other hand, a nitro group is an electron-withdrawing group. They withdraw the electrons from the aromatic ring. Withdrawing the negative charge from the ring will increase the stability of the compound in this case.</p><p>Phenoxide is stabilised by resonance effect only and it does not have any electron releasing group. So, it is more acidic than <em>o</em>-methyl phenol and <em>o</em>-methoxy phenol. But the absence of an electron-withdrawing group makes it less acidic than <em>o</em>-nitrophenol.</p>

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