See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

# Analysis of Position Isomerism **Position isomerism** occurs when atoms/groups can be attached at different positions on a carbon chain while maintaining the same molecular formula. ## Checking each option: **(1) $C_5H_{12}$ — alkane series** - Can form: n-pentane and isopentane (2-methylbutane) - **Exhibits position isomerism** ✗ **(2) $C_4H_8$ — alkene series** - Can form: but-1-ene and but-2-ene (double bond at different positions) - **Exhibits position isomerism** ✗ **(3) $C_6H_{14}$ — alkane series** - Can form: n-hexane, 2-methylpentane, 3-methylpentane, etc. - Multiple position isomers possible - **Exhibits position isomerism** ✗ **(4) $C_5H_{10}$ — alkene/cycloalkane series** - For alkenes: pent-1-ene and pent-2-ene would be position isomers - However, $C_5H_{10}$ **cannot have two different position isomers of the same functional type** - Pent-1-ene and pent-2-ene exist but are the only two possible structural arrangements; no third distinct position isomer exists without changing the carbon skeleton - **Does NOT exhibit position isomerism** ✓ **Answer: (4) $C_5H_{10}$** — This formula does not allow for true position isomerism as there are insufficient carbon atoms to place functional groups at distinctly different positions while maintaining structural distinction.