Final answer:
A polar covalent bond is present in water (H2O) because it involves an unequal sharing of electrons between hydrogen and oxygen, with oxygen pulling electrons more strongly towards itself due to its higher electronegativity.
Step-by-step explanation:
A polar covalent bond is a type of chemical bond where a pair of electrons is unequally shared between two atoms. In a molecule with polar covalent bonds, one of the atoms will have a greater electronegativity, or a stronger pull on the shared electrons, than the other atom, causing a partial positive charge on one end and a partial negative charge on the other. This polarizing effect results in a molecule with a dipole, meaning it has two distinct poles of charge.
From the given options, water (H2O) represents a molecule with a polar covalent bond. The electronegativity of oxygen is much higher than that of hydrogen, resulting in a greater pull of shared electrons towards the oxygen atom. This dynamic gives rise to a partial negative charge on the oxygen and a partial positive charge on the hydrogen atoms, fulfilling the criteria for polar covalent bonding.