The 2023 G.C.E. (A/L) Chemistry Paper I, held in early 2024 by the Department of Examinations, Sri Lanka: 50 multiple-choice questions in two hours, no calculators. In questions 31–40 one or more of the responses (a), (b), (c) and (d) is correct: choose (1) if only (a) and (b) are correct, (2) if only (b) and (c), (3) if only (c) and (d), (4) if only (d) and (a), and (5) for any other number or combination of correct responses. Questions 41–50 give two statements; choose the response that best fits them. Universal gas constant R = 8.314 J K⁻¹ mol⁻¹, Avogadro constant N_A = 6.022 × 10²³ mol⁻¹, Planck's constant h = 6.626 × 10⁻³⁴ J s, velocity of light c = 3 × 10⁸ m s⁻¹. Answers are from the official marking scheme, which accepts either (3) or (5) for Q7 and either (2) or (3) for Q49. Figures are shown exactly as printed. Each question links to the lesson it tests.