\mathrm{C(s) + 2H2(g) \rightarrow CH4(g)}; \Delta H = -74.8\ \mathrm{kJ\,mol^{-1}}. Which of the following diagrams (shown) gives an accurate representation of the above reaction? [R → reactants; P →

Question

\mathrm{C(s) + 2H2(g) \rightarrow CH4(g)}; \Delta H = -74.8\ \mathrm{kJ\,mol^{-1}}. Which of the following diagrams (shown) gives an accurate representation of the above reaction? [R → reactants; P → products]

![Question 65 as printed in the NEET 2025 booklet](/figures/neet-2025/q65.png)

Vishal Gupta · Accepted Answer

A. The reaction is exothermic (\Delta H = -74.8 kJ/mol), so the products must lie 74.8 kJ below the reactants, and there must still be an activation barrier between them. Only diagram (1) shows a hump followed by products lower than reactants.

Thermodynamics

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