WAEC Chemistry 2023 Paper

Concept:A non-polar covalent bond is formed when the shared pair of electrons is attracted equally by both bonded atoms, resulting in no separation of charge.Explanation:In $\mathrm{Cl}_2$, both atoms are identical chlorine atoms.So they have the same electronegativity.Both chlorine atoms attract the shared electron pair with equal strength.Therefore, the electrons are shared equally and distributed symmetrically.No partial positive or negative charge develops on either atom.Thus, $\mathrm{Cl}_2$ has a non-polar covalent bond and no permanent dipole moment.The other molecules are polar.$\mathrm{HCl}$, $\mathrm{NH}_3$, and $\mathrm{H}_2\mathrm{O}$ contain atoms with different electronegativities.This causes unequal sharing of electrons and forms polar covalent bonds.Hence, the molecule with a non-polar covalent bond is $\mathrm{Cl}_2$.Answer:Option C: $\mathrm{Cl}_2$