<u>Answer:</u> The expression for equilibrium constant in terms of concentration is given below.
<u>Explanation:</u>
Equilibrium constant is defined as the ratio of concentration of products to the concentration of reactants each raised to the power their stoichiometric coefficients. It is represented by 
For a general chemical reaction:

The
is written as:
![K_{eq}=\frac{[C]^c[D]^d}{[A]^a[B]^b}](https://tex.z-dn.net/?f=K_%7Beq%7D%3D%5Cfrac%7B%5BC%5D%5Ec%5BD%5D%5Ed%7D%7B%5BA%5D%5Ea%5BB%5D%5Eb%7D)
The concentration of pure solid and pure liquid are taken as 1 in equilibrium expression.
For the given chemical reaction:

The expression for
for the given reaction follows:
![K_{c}=\frac{[C]^2[D]^1}{[A]^1[B]^3}](https://tex.z-dn.net/?f=K_%7Bc%7D%3D%5Cfrac%7B%5BC%5D%5E2%5BD%5D%5E1%7D%7B%5BA%5D%5E1%5BB%5D%5E3%7D)
Here, A and B both are pure solid and pure liquid respectively. Thus, their concentration are taken as 1.
Thus, the expression becomes:
[tex]K_{c}=[C]^2[D]^1[/tex
Hence, the expression for equilibrium constant in terms of concentration is given above.