Final answer:
Option (C) 1000 atm and 100 °C is the best choice to maximize the yield of Z, as high pressure and low temperature favor the production of the product in an exothermic reaction according to Le Chatelier's principle.
Step-by-step explanation:
The given reaction 2X (g)+Y (g) → 2Z (g) ΔH=-335kJ indicates an exothermic process, releasing heat when proceeding forward. To determine which combination of pressure and temperature gives the highest yield of Z at equilibrium, we must consider Le Chatelier's principle. High pressure will favor the production of fewer moles of gas, and since we have fewer moles of gas on the product side (2 moles of Z compared to 3 moles of X and Y combined), we should select a high pressure. However, since the reaction is exothermic, high temperatures would shift the equilibrium to favor the reactants. Thus, a lower temperature is preferred to increase yield of Z. Therefore, the best combination is high pressure and low temperature.
Taking into account these factors, the best option is (C) 1000 atm and 100 °C, which employs both high pressure and low temperature to maximize the production of Z. Since a catalyst only affects the rate of the reaction and not the position of the equilibrium, option (E) would not impact the yield of Z relative to changes in pressure and temperature.