In this image, what letters represent nonpolar covalent bonds. select them by going by the blue letters.

The answer to your question is C, D, E, F, G, H, I, J

Explanation:

To know if a bond is nonpolar covalent we must calculate the difference of electronegativity if it is between 0 and 0.5, the bond is nonpolar.

A) N and H     3.04 - 2.2 = 0.84  

B) N and H     3.04 - 2.2 = 0.84

C) C and H     2.55 - 2.2 = 0.35                 Nonpolar covalent

D) C and N     3.04 - 2.55 = 0.49               Nonpolar covalent

E) C and C      2.55 - 2.55 = 0                    Nonpolar covalent

F) C and C      2.55 - 2.55 = 0                    Nonpolar covalent

G) C and H     2.55 - 2.2 = 0.35                 Nonpolar covalent

H) C and H     2.55 - 2.2 = 0.35                 Nonpolar covalent

I) C and H       2.55 - 2.2 = 0.35                 Nonpolar covalent

J) C and H      2.55 - 2.2 = 0.35                 Nonpolar covalent