Past Papers and Model Answers — O/L Science

How do I practise Past Papers and Model Answers?

1 question with a worked solution · 2 marks

1. 2023 · Paper I (MCQ) · 2 marks
   Two multiple-choice questions. Question 31 asks which gas in a list of four is NOT a greenhouse gas. Question 42 describes copper sulphate solution mixed with iron nails — the blue colour fading and the iron becoming coated — and asks which reaction type that best describes.
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   Q31: Answer B — Nitrogen (N₂). Methane, CO₂ and N₂O are greenhouse gases; nitrogen makes up ~78% of the atmosphere but does NOT trap heat significantly. Q42: Answer C — Displacement. Iron is more reactive than copper, so it displaces copper from copper sulphate solution: Fe + CuSO₄ → FeSO₄ + Cu. The blue colour fades as copper ions are removed; red/brown copper coats the iron nail.
   Source: Department of Examinations, Sri Lanka — G.C.E. O/L Science 2023, Paper I, Question 31 & Question 42 · https://doenets.lk/pastpapers

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Where does Past Papers and Model Answers fit in the syllabus?

Grade 11 · Term 3