Ammonia is manufactured by:
N2(g) + 3H2(g) ⇌ 2NH3(g); ΔfH° = –46.1 kJ mol–1
The various steps involved are:
(A) Condensation of mixture of gases
(B) Passing the gaseous mixture over catalyst
(C) Compression of the mixture of gases
(D) Recirculation of the gaseous mixture
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (C), (B), (A), (D)
In the Haber process the reaction is reversible and exothermic, with a decrease in the number of gas molecules (4 → 2). The conditions are therefore chosen as a high pressure (about 200 × 105 Pa), an optimum temperature of about 700 K and a catalyst of iron oxide with small amounts of \( \ce{K2O} \) and \( \ce{Al2O3} \):
\( \ce{N2(g) + 3H2(g) <=> 2NH3(g)} \) (iron oxide catalyst, about 700 K)
The steps follow the flow chart of the plant:
(C) Compression of the \( \ce{N2} \) + \( \ce{H2} \) mixture to about 200 atm, which shifts the equilibrium towards \( \ce{NH3} \).
(B) Passing the gases over the catalyst in the converter, where ammonia is formed.
(A) Condensation: the gas mixture is cooled and ammonia liquefies and is removed.
(D) Recirculation of the unreacted \( \ce{N2} \) and \( \ce{H2} \) back to the compressor.
Shortcut: recirculation can only be the last step; Option (1) is the only one ending with (D).
Note: This question is from the pre-rationalised NCERT book (2022-23). The topic is not there in the latest NCERT book (2026-27), and it is also out of the CUET 2026 syllabus.
NCERT (Pre-rationalised edition, 2022-23):
Ammonia – …
