2025 · Paper 1 · Chemistry
Question 6
The printed question, the official key, and each model’s JSON answer plus the reasoning it wrote.
Q06
Official A, B
Model answers
Claude Fable 5.1
Anthropic
A, B
Claude Fable 5.1 reasoning
Electronic configurations (Xe core = 54 electrons): - La (Z=57): [Xe]5d¹6s². La³⁺ → [Xe], 4f⁰ → diamagnetic. La²⁺ → [Xe]5d¹ (one unpaired electron) → paramagnetic. - Ce (Z=58): [Xe]4f¹5d¹6s². Ce⁴⁺ → [Xe], 4f⁰ → diamagnetic. Ce³⁺ → [Xe]4f¹ → paramagnetic. - Yb (Z=70): [Xe]4f¹⁴6s². Yb²⁺ → [Xe]4f¹⁴ → diamagnetic. Yb³⁺ → [Xe]4f¹³ → paramagnetic. - Lu (Z=71): [Xe]4f¹⁴5d¹6s². Lu³⁺ → [Xe]4f¹⁴ → diamagnetic. Lu²⁺ → [Xe]4f¹⁴5d¹ → paramagnetic. Thus: - (A) La³⁺ (f⁰), Ce⁴⁺ (f⁰): both diamagnetic ✔ - (B) Yb²⁺ (f¹⁴), Lu³⁺ (f¹⁴): both diamagnetic ✔ - (C) La²⁺ (d¹), Ce³⁺ (f¹): paramagnetic ✘ - (D) Yb³⁺ (f¹³), Lu²⁺ (d¹): paramagnetic ✘
GPT 6 Astra
OpenAI
A, B
GPT 6 Astra reasoning
No written reasoning was returned for this item.
GPT 5.6 Luna
OpenAI
A, B
GPT 5.6 Luna reasoning
No written reasoning was returned for this item.