It seems like it's right at the cut off for being a polar bond depending on what the cutoff is. In my textbook it says the cutoff for being polar covalent 0.5, but other sources say it can be as low as 0.4. A problem for my chemistry homework said the correct answer was that it was polar, but according to the electronegativity values they gave us, 3.44-3.04 is 0.4. Do people generally consider N-O a polar covalent bond?