1.What is the proper form of the equilibrium constant expression for the equation: N2(g)+O2(g)<=>2NO(g)

2.The of the reaction: NO2(g)+NO3(g)<=>N2O5(g) is K= 2.1x10^-20. What can be said about this reaction?

a.At equilibrium the concentration of products and reactants is about the same
b.At equilibrium the concentration of products is much greater than the concentration of reactants
c.At equilibrium the concentration of reactants is much greater than that of products
d.There are no reactants left over once the reaction reaches equilibrium

3.The acid HOCl (hypochlorous acid) is produced by bubbling chlorine gas through a suspension of solid mercury(II) oxide particles in liquid water according to the equation:
2HgO(s)+H2O(l)+2Cl2(g)<=>2HOCl(aq)+HgO x HgCl2(s)

What is the equilibrium constant expression for this reaction?