Question

In phenol carbon atom attached to -OH group undergoes -

1. SP³ hybridisation          
2. SP hybridisation
3. SP² hybridisation
4. No hybridisation

Answer 1

(c) sp² hybridisation
The carbon to which the hydroxyl group is bonded in phenol is sp² hybridised. The increased s-character of the carbon orbital used to form the C—O bond makes it more electron-withdrawing. Thus, conjugation with the aromatic ring would make the sp² hybridised oxygen atom more likely.