Step 1: Understanding Butanol-2
Butanol-2, also known as 2-butanol, is an alcohol compound. Alcohols have the general formula C\(_n\)H\(_{2n+1}\)OH. Butanol-2 is a specific isomer of butanol, where the hydroxyl group (OH) is attached to the second carbon of a four-carbon chain.
Step 2: Writing the Molecular Formula
Since butanol-2 is a four-carbon alcohol with a hydroxyl group, its molecular formula is C\(_4\)H\(_{10}\)O. The structure includes 4 carbon atoms, 10 hydrogen atoms, and 1 oxygen atom.
Step 3: Why the Other Options Are Incorrect
- (B) C\(_4\)H\(_8\)O\(_2\): This formula corresponds to butanoic acid, not butanol-2.
- (C) C\(_4\)H\(_{10}\): This formula represents butane, which is an alkane and not an alcohol.
- (D) C\(_4\)H\(_8\): This formula corresponds to 1-butene, an alkene, not an alcohol.
Thus, the correct answer is option (A) C\(_4\)H\(_{10}\)O.

How many molecules are secondary alcohol? 
Alcohols undergo a number of reactions involving the cleavage of C – OH bond. However, phenols do not undergo reactions involving the cleavage of C – OH bond. Alcohols are weaker acids than water. Alcohols react with halogen acids to form the corresponding haloaklanes. Phenols are stronger acids than alcohols. A charac- teristic feature of phenols is that they undergo electrophilic substitution reactions such as halogenation, nitration, etc. Since –OH group is a strong activating group, phenol gives trisubstituted products during halogenation, nitration, etc.