Is CN Polar or Nonpolar?

Answer: CN is a polar molecule because of the unequal distribution of charge between the carbon and nitrogen because of their large electronegativity difference. 

Electronegativity is defined on a one to four scale as the relative amount an element attracts electrons (i.e. how strong the element's pull on its valence electrons is). When you compare carbon's electronegativity (2.55) with nitrogens (3.04) you can see that there is a pretty large difference. Since nitrogen has a higher electronegativity value, it attracts the electrons more and therefore has a partial negative charge. This leaves carbon with a partial positive charge. The reason why nitrogen is more electronegative than carbon is because nitrogen has a large nucleus with more protons (positive charge) pulling on its valence electrons with the same amount of shielding (two electrons in the first orbital).

The lewis dot structure for CN is similar to that of HCN if you are interested in learning more about this kind of molecule.

CN Ball and Stick Model
CN Ball and Stick Model. Created with Avagadro.
What is CN utilized for in the real world?

Since CN and CN compounds are typically very poisonous, it finds usage in dissolving mining sediment, pest control and other industrial processes. Due to its reactivity, there are a large number of tests able to detect for the presence of cyanide including Prussian blue and copper/aromatic amine chemical detection mechanisms.