See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

**Step 1: Understand heat of hydrogenation** Heat of hydrogenation reflects the stability of a molecule. More stable compounds release less heat when hydrogenated (smaller ΔH). This is because stable molecules have lower energy and require less energy release to reach the saturated product. **Step 2: Identify structural features** - **1-Butene**: terminal C=C double bond - **trans-2-Butene**: internal C=C with trans configuration - **cis-2-Butene**: internal C=C with cis configuration - **1,3-Butadiene**: two conjugated C=C double bonds **Step 3: Evaluate stability using conjugation and steric effects** *Conjugation effect*: 1,3-Butadiene has conjugated double bonds, which delocalize electrons and increase stability significantly. *Steric effect*: - **cis-2-Butene** has methyl groups on the same side of the double bond → steric strain → destabilized - **trans-2-Butene** has methyl groups on opposite sides → no steric strain → highly stable *Position effect*: - Internal double bonds (2-butene) are more stable than terminal double bonds (1-butene) **Step 4: Ranking by stability** $$\text{trans-2-Butene} > \text{cis-2-Butene} > \text{1,3-Butadiene} > \text{1-Butene}$$ **trans-2-Butene is the most stable**, so it releases the least heat upon hydrogenation. **Answer: (B) trans-2-Butene**