Final answer:
HF has the largest dipole moment among Cl₂, LiF, ClF, and HF due to the significant electronegativity difference between hydrogen and fluorine and the polar nature of the bond.
Step-by-step explanation:
The molecule with the largest dipole moment among Cl₂, LiF, ClF, and HF is HF (hydrogen fluoride). This is because HF has a significant electronegativity difference between hydrogen (H) and fluorine (F), leading to a strong polar bond. The bond dipoles in HF are also greatly affected by the small size of the H atom compared to F, leading to a large overall dipole moment.
On the other hand, Cl₂ is nonpolar because it consists of two identical chlorine atoms, meaning there is no electronegativity difference and hence no dipole moment. In the cases of LiF and ClF, although there are electronegativity differences, HF still has the largest dipole moment due to fluorine's particularly high electronegativity and the bond's polarity.