Which of the following alkanes has a straight-chain structure?
Cyclopentane (C5H10)
Isobutane (C4H10)
2 - methyl propane (C4H10)
Pentane (C5H12)
Correct answer is D
Pentane (C5H12) is a straight-chain alkane. Alkanes are hydrocarbons with the general formula CnH2n+2. They are called straight-chain alkanes if all the carbon atoms are connected in a continuous chain without any branches. Butane and Isobutane are both C4H10, but Isobutane has a branched structure, not a straight chain. Cyclopentane (C5H10) is a cycloalkane, not a straight-chain alkane.