write the equilibrium constant expressions Kp for each of the following

N2O <===> 2NO2
2NO + Br2 <====> 2NOBr
2SO2 + O2 <====> 2SO3
4NH3 + 5O2 <====> 4NO + 6 H2O

These easy to do. We don't do your home work for you. If you don't know what to do, please explain in detail the problem you are having.

well what is the equilibrium constant

Keq is a number, evaluated experimentally. The Keq expression is

(partial pressure of products)/(partial pressure of reactants) and raise each one to the power indicated by the coefficient. Here is the one as an example. I shall be happy to check your work for the others.

Kp = pSO3^2/pSO2^2*pO2
It is read this way:
partial pressure of SO3 squared divided by the product of partial pressure of SO2 squared times partial pressure oxygen.

This may sound wordy but it is the definition of Kp. Almost word for word what my chemistry prof said long long ago.

"The product of the partial pressures of the products of the reaction divided by the product of the partial pressures of the reactants, each raised to a power indicated by the coefficient in the balanced chemical equation, is a constant, Kp."

To write the equilibrium constant expression for each reaction given, we need to express the ratio of the product concentrations to the reactant concentrations, each raised to their respective stoichiometric coefficients.

1. For the reaction:
N2O <===> 2NO2

The equilibrium constant expression (Kp) is:
Kp = [NO2]^2 / [N2O]

2. For the reaction:
2NO + Br2 <====> 2NOBr

The equilibrium constant expression (Kp) is:
Kp = [NOBr]^2 / ([NO]^2 * [Br2])

3. For the reaction:
2SO2 + O2 <====> 2SO3

The equilibrium constant expression (Kp) is:
Kp = [SO3]^2 / ([SO2]^2 * [O2])

4. For the reaction:
4NH3 + 5O2 <====> 4NO + 6H2O

The equilibrium constant expression (Kp) is:
Kp = ([NO]^4 * [H2O]^6) / ([NH3]^4 * [O2]^5)

You can write these expressions by raising the concentration of each product to the power of its respective stoichiometric coefficient and multiplying them, then dividing by the concentration of each reactant raised to the power of its stoichiometric coefficient.