Q.F. The homologous series of alcohols has general molecular formula .........
a. CnH2n+1OH b. CnH2n+2OH c. CnH2n-2OH c. CnH2nOH
(NOTE: the source itself prints the option letter 'c' twice, for CnH2n-2OH and CnH2nOH -- a printing error in the book, most likely meant to be 'd' for the second one; reproduced here exactly as printed rather than silently corrected.)

Step 1. The alcohol functional group is -OH attached to a saturated (alkyl) carbon skeleton; the parent alkyl group itself follows the general formula CnH2n+1- (an alkane, CnH2n+2, minus one hydrogen for the point of attachment).

Step 2. Attaching -OH to that CnH2n+1- alkyl group gives the alcohol homologous series general formula CnH2n+1OH -- matching methanol (CH3OH, n=1), ethanol (C2H5OH, n=2), and so on, each successive member differing by one -CH2- unit exactly as a homologous series requires (section 14.3.2). …

Deriving the alcohol series' general formula from the underlying saturated alkyl group's own formula (CnH2n+1-) plus the -OH functional gr …

• Confusing the alcohol series formula with the plain alkane formula (CnH2n+2), forgetting that replacing one H with -OH does not change the …