Question

Why are the molecules of hydrocarbons nonpolar?

Answer 1

Molecules are symetrical and charges are therefore spread out evenly.

Explanation:

Let's take for example methane, `"CH"_4`. Even though the individual bonds of `"C"-"H"` are polar, carbon atoms are more electronegative than hydrogen atoms. The shape provides a balanced charge:
https://embed.molview.org/v1/?mode=balls&cid=297

As all bonds are the same and the molecule is symmetrical, each half as the same number of and type of bonds, so the electrons are generally spread out evenly.