Question

what is the electronegativity value of N3C?

Answer 1

Electronegativity calculated by subtracting the higher electronegative element by the lower electronegative element. Electronegativity values can be found on a electronegativity chart. In this case, Nitrogen (3.04) is more electroneg. than Carbon (2.55).

3.04-2.55= 0.49 That is your answer
In case you wanted to know, this number tells you that it's a covalent bond.