Chiral compounds possess a stereocenter with four different substituents

Steps:

• Parse each name to determine the carbon chain and positions of Cl and methyl group.
• Identify the carbon atom bearing the Cl and list its four attached groups.
• Compare the groups pairwise to check for identical substituents.
• Confirm chirality only if all four groups differ in structure.

Why C is correct:

• In 3-chloro-2-methylbutane (CH3CH(CH3)CHClCH3), the C3 stereocenter bonds to Cl, H, CH3, and CH(CH3)CH3 (isopropyl), satisfying the four different substituents rule for chirality.

Why the others are wrong:

• A. Primary Cl carbon has two H atoms; branched C3 has two identical CH3 groups.
• B. C2 in 2-chloro-3-methylbutane bonds to Cl, H, and two similar CH3-bearing chains that are structurally equivalent.
• D. C3 in 3-chloropentane bonds to Cl, H, and two identical CH2CH3 groups.

Final answer: C