Question

How can a molecule be nonpolar when it consists of atoms that have different electronegativities?

Answer 1

You must calculate the EN larger number subtracted by the smaller number, and also draw it too.
Then you have to look at a scale;

Non-polar: 0-0.5
Polar Covalent: 0.6-1.6
Ionic: 1.7+

If you draw the molecule and they are symmetrical it will be non-polar but with polar bonds if you calculate the EN.