See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Solution To find a molecule with exactly **two sigma (σ) and two pi (π) bonds**, analyze the structure of each option: ## Analysis of Each Option: **(A) $C_2H_4$ (Ethene)** - Structure: $H_2C=CH_2$ - Bonds: 5σ bonds (C-C single + 4 C-H) + 1π bond - ✗ Not correct **(B) $N_2F_2$** - Structure: $F-N=N-F$ (assuming cis/trans isomer) - Bonds: 2σ bonds (N-F bonds) + 1π bond (N=N double bond) - ✗ Not correct **(C) $C_2H_2Cl_2$** - Structure: $ClH_2C-CH_2Cl$ (saturated, no double bonds) - Bonds: All single bonds only - Count: 8σ bonds, 0π bonds - ✗ Not correct **(D) HCN (Hydrogen Cyanide)** - Structure: $H-C\equiv N$ - Bonds breakdown: - **1σ bond** (H-C single bond) - **1σ bond** (C-N single bond, part of triple bond) - **2π bonds** (two perpendicular π bonds in the C≡N triple bond) - **Total: 2σ + 2π** ✓ ## Answer: **(D) HCN** The triple bond in HCN ($C\equiv N$) consists of one σ and two π bonds. Combined with the H-C σ bond, we get exactly two σ and two π bonds.