The bonding pair of electrons in a Hydrogen Chloride molecule is pulled towards the chlorine atom because

The correct answer is that chlorine is more electronegative than hydrogen. Electronegativity is a measure of an atom's ability to attract electrons towards itself in a covalent bond. Chlorine has a higher electronegativity than hydrogen, which means that the bonding pair of electrons in a hydrogen chloride molecule is pulled more towards the chlorine atom than towards the hydrogen atom. This creates a partial positive charge on the hydrogen atom and a partial negative charge on the chlorine atom, forming a polar molecule.