A molecule with a polar covalent bond between atoms exhibits

A covalent bond is formed when two atoms share a pair of electrons. When the two bonded atoms have different electronegativities, they do not attract the shared electron pair equally. The more electronegative atom pulls the electron pair closer to itself, creating a partial negative charge on that atom and a partial positive charge on the other. This results in a polar covalent bond.

Therefore, a polar covalent bond is characterised by the unequal sharing of an electron pair between atoms.

By contrast, when two atoms of the same element (or very similar electronegativity) bond, the electrons are shared equally, producing a non-polar covalent bond (e.g., H₂, Cl₂, O₂).

The options mentioning "lone pair" are incorrect in this context. A lone pair is an unshared pair of electrons that belongs entirely to one atom and is not involved in bonding between the two atoms. Covalent bonds (whether polar or non-polar) involve bonding pairs, not lone pairs.