See image — Hydrocarbons Chemistry Question

💡 Solution & Explanation

The starting material is 2-methylbutane (isopentane): CH3-CH(CH3)-CH2-CH3. We number the carbons for clarity: C1: CH3 (terminal) C2: CH (bearing CH3 branch) - already has 3 different groups? Let's check after chlorination. C3: CH2 C4: CH3 (terminal) Plus the branch CH3 on C2. For free-radical monochlorination, we consider all distinct hydrogen positions: Position 1 (C1 methyls - the two equivalent CH3 groups on C1 and the branch CH3 on C2): Chlorination at any of these equivalent CH3 groups (C1 or branch CH3 on C2) gives 1-chloro-2-methylbutane: ClCH2-CH(CH3)-CH2-CH3. C2 now has four different groups: H, CH3, CH2Cl, CH2CH3 → C2 becomes a chiral center. Count: 1 chiral center generated. Position 2 (C2, the methine CH): Chlorination here gives 2-chloro-2-methylbutane: CH3-CCl(CH3)-CH2-CH3. C2 has: Cl, CH3, CH3, CH2CH3 - two identical CH3 groups, so NOT a chiral center. Count: 0 chiral centers. Position 3 (C3, the CH2): Chlorination here gives 2-methyl-3-chlorobutane (wait, let me re-examine): CH3-CH(CH3)-CHCl-CH3. C3 now has: H, Cl, CH(CH3)2... wait. The structure is CH3-CH(CH3)-CHCl-CH3. C3 has four groups: H, Cl, CH(CH3)-CH3 (i.e., the C2 side), and CH3 (C4 side). These four groups are all different → C3 is a chiral center. Also, C2 now has: H, CH3, CH3... wait. C2 in this product: attached to CH3 (C1), CH3 (branch), H, and CHCl-CH3 (C3 side). C2 groups: H, CH3, CH3, CHClCH3 - two CH3 groups identical → C2 is NOT chiral. So only C3 is chiral. Count: 1 chiral center. Position 4 (C4, the terminal CH3): Chlorination gives CH3-CH(CH3)-CH2-CH2Cl. C4: H2, Cl → not chiral (two H's). C2: H, CH3, CH3, CH2CH2Cl → two CH3 identical, NOT chiral. Count: 0 chiral centers. Summary of distinct products and chiral centers: - Chlorination at C1/branch CH3 → 1-chloro-2-methylbutane: 1 chiral center (C2) - Chlorination at C2 → 2-chloro-2-methylbutane: 0 chiral centers - Chlorination at C3 → 3-chloro-2-methylbutane: 1 chiral center (C3) - Chlorination at C4 → 1-chloro-3-methylbutane (neopentyl-type): 0 chiral centers Wait - the question asks for the number of chiral centers GENERATED across all monochlorination products. Reconsidering: we need to count the total number of chiral centers present across all possible monochlorinated products. Product 1 (from C1 or branch CH3): has 1 chiral center Product 2 (from C2): has 0 chiral centers Product 3 (from C3): has 1 chiral center Product 4 (from C4): has 0 chiral centers But the answer is 2. This means the question asks: in how many of the distinct monochlorinated products is a chiral center generated? Products 1 and 3 each generate 1 chiral center, giving a total count of 2 products with chiral centers, or 2 chiral centers total across all products. Alternatively, interpreting as: the total number of new chiral centers created = 1 (in product from C1/branch) + 1 (in product from C3) = 2 chiral centers generated overall. The other options fail because: option (a) 1 undercounts by missing one of the two chiral-center-generating positions; option (c) 3 and (d) 4 overcount since chlorination at C2 and C4 do not generate chiral centers. Therefore, the correct answer is B.