Le Chatelier's Principle for Endothermic Reaction with Gas Volume Increase

Steps:

• Identify the reaction as endothermic (ΔH > 0), so higher temperature shifts equilibrium right to absorb heat, increasing NO yield.
• Calculate change in gas moles: reactants 9 mol, products 10 mol (Δn = +1), so lower pressure shifts equilibrium right to produce more moles, increasing NO yield.
• Combine factors: high temperature favors endothermic forward reaction; low pressure favors increased moles on product side.
• Select option matching both: high T and low P maximizes NO at equilibrium.

Why C is correct:

• High temperature drives endothermic reaction forward (Le Chatelier's principle); low pressure favors side with more gas moles (Δn > 0).

Why the others are wrong:

• A: High pressure shifts left (fewer moles), decreasing NO despite high T.
• B: Low temperature shifts left (exothermic reverse), decreasing NO despite high P.
• D: Low temperature shifts left, decreasing NO despite low P.

Final answer: C