Which formula represents a molecule with the most polar bond? 1. \( F_{2} \) \( 2 \mathrm{H}_{2} \) 3. HCl 4. HBr

To determine which formula represents a molecule with the most polar bond, we need to consider the electronegativity differences between the atoms in each molecule. The greater the difference in electronegativity, the more polar the bond. 1. **\( F_{2} \)**: This molecule consists of two fluorine atoms. Since both atoms are the same, the electronegativity difference is 0, resulting in a nonpolar bond. 2. **\( H_{2} \)**: This molecule consists of two hydrogen atoms. Similar to \( F_{2} \), the electronegativity difference is 0, resulting in a nonpolar bond. 3. **HCl**: This molecule consists of hydrogen and chlorine. The electronegativity of hydrogen (H) is approximately 2.1, and that of chlorine (Cl) is approximately 3.0. The difference is: \[ \Delta \text{EN} = 3.0 - 2.1 = 0.9 \] This indicates a polar bond. 4. **HBr**: This molecule consists of hydrogen and bromine. The electronegativity of bromine (Br) is approximately 2.8. The difference is: \[ \Delta \text{EN} = 2.8 - 2.1 = 0.7 \] This also indicates a polar bond, but it is less polar than HCl. Now, comparing the polarities: - \( F_{2} \) and \( H_{2} \) are nonpolar. - HCl has a polar bond with a difference of 0.9. - HBr has a polar bond with a difference of 0.7. Thus, the molecule with the most polar bond is **HCl**.