At 2273 K the equilibrium constant for the reaction

Question

2 NO(g) « N2(g) + O2(g) KC = 2400
What would be the equilibrium concentration of N2 if the initial concentration of NO was 0.1778 M?

Answer 1

Do you mean for this reaction be be written as
N2 + O2 ==> 2NO with Kc = 2400. That's the way you have your arrows.