Final answer:
The key features of the Haber process are high pressure and high temperature. High pressure is used to shift the equilibrium towards the formation of ammonia, while high temperature is required to accelerate the reaction rate. A catalyst is used to enhance the reaction at relatively moderate temperatures. Therefore, the correct option is D.
Step-by-step explanation:
The key features of the Haber process are high pressure and high temperature. The process involves the reaction of nitrogen and hydrogen to produce ammonia:
N₂(g) + 3 H₂(g) → 2 NH₃(g)
High pressure (approximately 150-250 atm) is used to shift the equilibrium towards the formation of ammonia. Additionally, high temperature (around 400-500 °C) is required to accelerate the reaction rate. Although low temperatures favor product formation, the reaction rate at low temperatures is too slow, so a catalyst is used to enhance the reaction.