Answer: option 3, CH₄.
Explanation:
1) A molecule is polar if and only if at least one bond is polar and the polar bonds are not symmetrically distributed around the center of the molecule.
2) CH₄ has four C-H bonds symmetrically distributed arond the C atom, so it is not possible for it to be polar, which is what answers the question.
3) The bonds in H₂S are not symmetrical distributed around the S atom, because S has two additional pair of non-bonding electrons which bends the molecule, so it is polar.
4) HCl is polar since there is one only H-Cl bond which is polar because the difference in the electronegativities of the H and Cl.
5) NH₃ is polar because the N atom has an additional pair of non bonding electrons, which bends the molecule.
