Calculate Kp at higher temperature and compare to determine reaction type Steps:

• For X + Y ⇌ 2Z, Kp = (P_Z)^2 / (P_X × P_Y).
• Substitute partial pressures at T2: Kp = (5)^2 / (6 × 9) = 25 / 54.
• 25/54 ≈ 0.46 < 2 (Kp at T), so Kp decreases as T increases.
• Decrease in Kp with rising temperature means exothermic (van't Hoff equation: positive ΔH would increase Kp).

Why D is correct:

• Kp(T2) = 25/54 < Kp(T) = 2 confirms exothermic, as higher T favors reactants for exothermic reactions.

Why the others are wrong:

• A: 54/25 ≈ 2.16 > 2 implies endothermic, but actual Kp = 25/54 < 2.
• B: 54/25 > 2 implies exothermic, but 54/25 is reciprocal of actual Kp.
• C: 25/54 is correct Kp value but wrongly labels endothermic (should be exothermic).

Final answer: D