Question

Why is methane, CH4, a nonpolar compound?

Answer 1

To test for polarity you have to check the individual bonds.  C - H bond is a nonpolar bond since the electronegativities are VERY close to one another.  Since all the bonds are nonpolar the compound is non polar.

Answer 2

The electronegativity value of C and H are 2.5 and 2.1 respectively.  

The electronegativity difference between the C and H atom is 0.4

When the electronegativity difference below 0.5 is observed that bond is a nonpolar covalent bond. C-H is a nonpolar covalent bond. CH₄ has 4 nonpolar C-H bond and the CH₄ molecule is nonpolar.