Answer is: 3) H2O and HCl.
Polar molecules are water (H₂O) and hydrochloric acid (HCl).
Nonpolar molecules are carbon(IV) oxide (CO₂) and methane (CH₄).
Carbon(IV) oxide is nonpolar because CO₂ is linear molecule and the oxygen atoms are symmetrical (bond angles 180°).
Water is polar because of the bent shape of the molecule.
Hydrochloric acid has polar covalent chemical bond where hydrogen has oxidation umber +1 and chlorine oxidation number -1.
In molecule of methane (CH₄) all the atoms around the central element (carbon) are equivalent (four hydrogens) and it has a net dipole moment of 0 (vectors of dipole moments cancel each other, dipole moment is zero).
