Free radical chlorination of 2-methylbutane yields six C5H11Cl isomers Steps:

• Identify four types of non-equivalent hydrogens in CH3CH(CH3)CH2CH3: primary on geminal methyls (6H), tertiary at C2 (1H), secondary at C3 (2H), primary at terminal methyl (3H).
• Substitution at geminal methyls creates chiral center at C2 (CH2Cl, CH3, H, CH2CH3), giving two enantiomers.
• Substitution at tertiary C2 yields (CH3)2CClCH2CH3, achiral (symmetric methyls).
• Substitution at C3 creates chiral center (Cl, H, CH3, CH(CH3)2), giving two enantiomers.
• Substitution at terminal methyl yields CH3CH(CH3)CH2CH2Cl, achiral (no stereocenter). Why C is correct:
• Four substitution sites produce two achiral and two chiral products (each with a pair of enantiomers), totaling 2(1) + 2(2) = 6 isomers per constitutional isomer definition. Why the others are wrong:
• A: Ignores optical isomers, counting only four constitutional products.
• B: Underestimates by treating one chiral product as single (e.g., racemic as one).
• D: Overcounts nonexistent isomers, like assuming extra chiral centers.

Final answer: C