How many structural isomers are possible for butane (C4H10)?
Correct: B
Butane (C4H10) has two structural isomers: 1. n-butane (straight chain: CH3-CH2-CH2-CH3) and 2. Isobutane (2-methylpropane, a branched chain: CH3-CH(CH3)-CH3). These two compounds have the same molecular formula but different structural arrangements of atoms.