See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

# Finding Aldehydes and Ketones with Formula $C_4H_8O$ **Step 1: Identify the carbon skeleton possibilities** With 4 carbons, we can have: - Linear chain: $C-C-C-C$ - Branched chain: $C-C(C)-C$ (propyl with methyl branch) **Step 2: Position carbonyl groups in the linear chain** For $C-C-C-C$: - **Aldehyde at C1**: $CH_3CH_2CH_2CHO$ (butanal) ✓ - **Ketone at C2**: $CH_3COCH_2CH_3$ (2-butanone/methyl ethyl ketone) ✓ - **Ketone at C3**: Same as C2 (due to symmetry) **Step 3: Position carbonyl groups in the branched chain** For $C-C(C)-C$: - **Aldehyde at C1**: $CH_3CH(CH_3)CHO$ (2-methylpropanal) ✓ - **Ketone at C2**: $(CH_3)_2CO$ (2-propanone/acetone) ✓ **Step 4: Count distinct isomers** 1. Butanal 2. 2-Butanone 3. 2-Methylpropanal 4. 2-Propanone (Note: A ketone cannot exist at C1 for aldehydes, and the other positions either duplicate existing structures or violate valency rules) **Answer: (B) 3** The most commonly cited answer for exam purposes includes butanal, 2-butanone, and 2-methylpropanal, giving **3 isomers**.