ANS:C - High pressure, high reactants concentration, low temperature.

The set of conditions favorable for the maximum yield of ammonia by Haber's process is High pressure, high reactants concentration, low temperature. Here's why:

1. High Pressure: According to Le Chatelier's Principle, increasing the pressure favors the reaction that produces fewer gas molecules. In the case of the Haber process, the formation of ammonia (NH3) involves a decrease in the number of gas molecules, so higher pressure shifts the equilibrium towards the formation of more ammonia molecules, increasing the yield.
2. High Reactants Concentration: Increasing the concentration of reactants provides more molecules to react, which increases the chances of successful collisions between molecules, thus increasing the rate of ammonia formation. This also helps in shifting the equilibrium towards the products, favoring the formation of more ammonia.
3. Low Temperature: While the Haber process is exothermic (releases heat), according to Le Chatelier's Principle, reducing the temperature will shift the equilibrium towards the exothermic direction to counteract the decrease in temperature. Therefore, operating at a lower temperature promotes the formation of more ammonia to compensate for the decrease in temperature, leading to a higher yield of ammonia.