What is the equilibrium constant for the reaction
H2(g) CO2(9) = H2O(g) + CO(g)?

See explanation

Explanation:

We have to remember that for any equilibrium expression constant we can use the general reaction:

With a equilibrium expression:

We have to divide products by reagents and use the coefficient (in the balanced reaction) as exponents. So:

The reaction is already balanced. So, we can write the equilibrium expression:

In this case, all the compounds have gaseous state (g). So, we can change the concentration ([]) by the pressure of each compound:

I hope it helps!