Q: Which one of the following is an endothermic reaction?
(a)CH₄ (g) + 2O₂ (g) → CO₂ (g) + 2O₂ (g)
(b)C₆H₁₂O₆ (aq) + 6O₂ (g) → 6CO₂ (g) + 6H₂O (l)
(c)N₂ (g) + 3H₂ (g) → 2NH₃ (g)
(d)2Pb(NO₃)₂ (s) → 2PbO (s) + 4NO₂ (g) + O₂ (g)
Correct Answer: (d)
The correct answer is (c): N2 (g) + 3H2 (g) → 2NH3 (g). Subject: Environment & Ecology | Sub-topic: Climate Change & Greenhouse Gases Note: This answer was determined through AI-based research. Verify against the official answer key when available.