See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

# Finding Stereoisomers in 3-Penten-2-ol **Identifying the structure:** $CH_3CH=CHCH(OH)CH_3$ **Step 1: Locate stereocenters** Only the carbon bearing the $-OH$ group (the secondary alcohol carbon) is a stereocenter, as it has four different groups attached: - $-OH$ - $-H$ - $-CH_3$ - $-CH=CHCH_3$ **Step 2: Account for the double bond** The $C=C$ double bond (between C-3 and C-4) cannot rotate, creating geometric isomers: - **cis configuration** (both methyls on same side) - **trans configuration** (methyls on opposite sides) **Step 3: Count stereoisomers** For each geometric isomer, the stereocenter can have two configurations: - **R or S** (from Cahn-Ingold-Prelog priority rules) This gives: - cis-3R-penten-2-ol - cis-3S-penten-2-ol - trans-3R-penten-2-ol - trans-3S-penten-2-ol **Total = 4 stereoisomers** **Answer: (D) 4**