Question

Which is nonpolar: `CF_4` or `CH_2F_2`?

Answer 1

`CF_4` is non-polar.

Explanation:

Molecular polarity results from the vector sum of the individual `C^(delta+)rarrF^(delta-)` dipoles. Given a tetrahedron (and `CF_4` certainly assumes this structure), the `C-F` dipoles sum to `0` (remember that the vector sum is the geometric sum). The `C-H` bond is fairly non-polar, and thus their equivalent vector sum with `C-F` dipoles is non-zero.

The same situation obtains when non-polar `C(Cl)_4` is compared to polar chloroform, or (more polar) methylene chloride.