Final answer:
The amount of CO in the flask when the system returns to equilibrium is 0.17 mol.
Step-by-step explanation:
To find the amount of CO in the flask when the system returns to equilibrium, we need to consider the given equation:
CO(g) + H₂O(g) = CO₂(g) + H₂(g)
Given that 0.17 mol of H₂ and 0.17 mol of CO are present, we can use the stoichiometry of the equation to determine the amount of CO₂ produced:
Moles of CO₂ produced = 0.17 mol of CO
Therefore, the amount of CO in the flask when the system returns to equilibrium is 0.17 mol.