The sum of sigma () and pi () bonds in Hex-1,3-dien-5-yne is ______________. — JEE Mains Chemistry Past Papers Chemistry Question

💡 Solution & Explanation

**Step 1: Draw the structure of Hex-1,3-dien-5-yne** Hex-1,3-dien-5-yne has 6 carbons with: - Double bonds at positions 1 and 3 - Triple bond at position 5 Structure: CH₂=CH–CH=CH–C≡CH **Step 2: Count sigma (σ) bonds** Sigma bonds include: - All single bonds: C–C bonds (5) + C–H bonds (8) - Sigma bonds in double bonds: 2 (one per C=C) - Sigma bonds in triple bond: 1 (the σ component of C≡C) Total σ bonds = 5 + 8 + 2 + 1 = **16** **Step 3: Count pi (π) bonds** Pi bonds exist only in multiple bonds: - First double bond (C₁=C₂): 1 π bond - Second double bond (C₃=C₄): 1 π bond - Triple bond (C₅≡C₆): 2 π bonds Total π bonds = 1 + 1 + 2 = **4** **Step 4: Calculate the sum** Sum of σ and π bonds = 16 + 4 = **20** Therefore, the answer is **20**.