List of top Chemistry Questions on Equilibrium asked in EAMCET

For the reaction $N _{2}( g )+ O _{2}( g ) \rightleftharpoons 2 NO ( g )$ the equilibrium constant is $K _{1}$. The equilibrium constant is $K _{2}$ for the reaction $2 NO ( g )+ O _{2}( g ) \rightleftharpoons 2 NO _{2}( g ) .$ What is $K$ for the reaction $NO _{2}( g ) \rightleftharpoons 1 / 2 N _{2}( g )+ O _{2}( g ) ?$