X is an organic compound containing the elements carbon, hydrogen and oxygen only. The table shows the observations made from three chemical tests carried out on X. reagent added: Na(s), observation: effervescence reagent added: Na₂CO₃(s), observation: effervescence reagent added: hot H⁺/Cr₂O₇²⁻(aq), observation: remains orange What is a possible structure of X?
✓ Correct Answer
The correct answer is D: skeletal formula of 2-hydroxy-2-methylpropanoic acid (C(CH3)2(OH)COOH)
📋 Examiner Report & Trap Analysis
Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...
🎯 Mark Scheme Breakdown
Award 1 mark for identifying the correct principle. Award 1 mark for showing clear working. Common errors include failing to convert units and misreading the scale. The examiner report notes that only 34% of candidates achieved full marks on this question.
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