Structural isomers of C4H10O alcohols

Steps:

• Determine possible carbon skeletons: straight chain (butane) and branched (isobutane).
• For straight chain, attach OH to primary (C1) or secondary (C2) carbons, yielding 1-butanol and 2-butanol.
• For branched chain, attach OH to primary carbon of isobutane (2-methyl-1-propanol) or tertiary carbon (2-methyl-2-propanol).
• Confirm no duplicates or additional skeletons fit C4H10O.

Why C is correct:

• Structural isomers differ in carbon connectivity; exactly four alcohols satisfy the formula via distinct OH placements on C4 skeletons.

Why the others are wrong:

• A: Underestimates by ignoring branched chains.
• B: Misses the tertiary alcohol isomer.
• D: Overcounts, as no fifth unique structure exists.

Final answer: C