2025 · Paper 2 · Chemistry
Question 12
The printed question, the official key, and each model’s JSON answer plus the reasoning it wrote.
ChemistryPaper 2Numerical
Q12
Official 4 – 4.25
Model answers
Claude Fable 5.1
Anthropic
Correct4 / 4
4.17
Claude Fable 5.1 reasoning
**Setup:** Let [A]₀ = a, [R]₀ = 10a. At 40 % completion: [A] = 0.6a, [R] = 10a − 0.4a = 9.6a. - True rate = k[A][R] = k(0.6a)(9.6a) = 5.76 k a² - Pseudo‑first‑order rate = k′[A] = k[R]₀[A] = k(10a)(0.6a) = 6.00 k a² Relative error = (6.00 − 5.76)/5.76 × 100 = 0.24/5.76 × 100 ≈ 4.17 %
GPT 6 Astra
OpenAI
Correct4 / 4
4.17
GPT 6 Astra reasoning
No written reasoning was returned for this item.
GPT 5.6 Luna
OpenAI
Correct4 / 4
4.17
GPT 5.6 Luna reasoning
No written reasoning was returned for this item.