Answer
a) equilibrium constant $k_{eq} = \frac{[CO_{2}]^{2}}{[CO]^{2}[O_{2}]} $
b) equilibrium constant $k_{eq} = \frac{[NO]^{2}}{[N_{2}][O_{2}]}$
c) equilibrium constant $k_{eq} = \frac{[SbCl_{3}][Cl_{2}]}{[SbCl_{5}]}$
d) equilibrium constant $ k_{eq} = \frac{[COCl_{2}]}{[CO][Cl_{2}]}$
Work Step by Step
For any equilibrium reaction say,
$ aP + bQ \leftrightharpoons cR + dS $
Where P, Q are reactants and R, S are products.
a,b,c,d are stoichiometric co-efficient.
Now, we can write the equilibrium expression for this reaction as follows:
$ k_{eq} = \frac{[R]^{c}[S]^{d}}{[P]^{a}[Q]^{b}}$
So, this is the general equilibrium expression for any chemical reaction.
