<u>Answer:</u> The pressure equilibrium constant for the reaction is 
<u>Explanation:</u>
We are given:
Initial partial pressure of methane = 0.60 atm
Initial partial pressure of water vapor = 2.6 atm
Equilibrium partial pressure of hydrogen gas = 1.4 atm
The chemical equation for the reaction of methane gas and water vapor follows:

<u>Initial:</u> 0.60 2.6
<u>At eqllm:</u> 0.60-x 2.6-x x 3x
Evaluating the value of 'x':

So, equilibrium partial pressure of methane gas = (0.60 - x) = [0.60 - 0.467] = 0.133 atm
Equilibrium partial pressure of water vapor = (2.6 - x) = [2.6 - 0.467] = 2.133 atm
Equilibrium partial pressure of carbon monoxide gas = x = 0.467 atm
The expression of
for above equation follows:

Putting values in above equation, we get:

Hence, the pressure equilibrium constant for the reaction is 