Given below are two reactions, involved in the commercial production of dihydrogen (H₂). The two reactions are carried out at temperature "T₁" and "T₂", respectively
C(s) + H₂O(g)→(T₁) CO(g) + H₂(g)
CO(g) + H₂O(g)→ _(Catalyst)^(T₂) CO₂(g) + H₂(g)
The temperatures T₁ and T₂ are correctly related as :

Solution

Chemistry ma’am · 3 steps

Making water gas needs red-hot coke; the shift step runs much cooler with a catalyst.

1. Water-gas reaction. Steam is passed over red-hot coke at about 1270 K: C(s) + H₂O(g) → CO(g) + H₂(g). The product mixture of CO and H₂ is called water gas. This reaction is strongly endothermic, so it needs a very high temperature. That temperature is T₁.
2. Water-gas shift. To get more H₂, the CO in water gas is reacted with more steam: CO(g) + H₂O(g) → CO₂(g) + H₂(g). This step is exothermic, so it is run at a much lower temperature, about 673 K, with an iron chromate catalyst to keep it fast. That temperature is T₂.

   T₁ ≈ 1270 K > T₂ ≈ 673 K

3. So. The first reaction runs hotter than the second, so T₁ > T₂, which is option (d).

The idea to keep. Water gas is made at about 1270 K over red-hot coke. The shift reaction runs at about 673 K with an iron chromate catalyst. An endothermic step needs heat, and an exothermic step is kept cooler.

Answer from the NTA final answer key. Solution by PrepWiser.