Their general formula is C_nH_2n+1OH or C_nH_2n+2O. These are of following types, depending upon the no. of OH groups. (i) Monohydric alcohol:- Contains one -OH group only, eg. C₂H₅OH (ii) Dihydric alcohol :- Contains two -OH groups- eg. glycol (iii) Trihydric alcohol:- Contains three -OH groups eg. glycerol (iv) Polyhydric alcohol :- Contains more than three -OH groups- eg, sorbitol, mannitol.