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AQA Specimen Paper 2 Q11
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![28 Butanone is reduced in a two-step reaction using NaBH4 followed by dilute hydrochloric acid. Write an overall equation for the reduction of butanone using [H] to represent the reductant. By considering the mechanism of the reaction, explain why the product has no effect on plane polarised light. [1 mark] [6 marks] 11 . 1 1 1 . 2 1 1 Barcode Typesetter code<br />](https://learnah.org/wp-content/uploads/2018/08/Specimen_QP_-_Paper_2_AQA_Chemistry_A-Level_11-1.jpg)
![MARK SCHEMEA-level ChemistrySpecimen paper 2 Marking guidance Mark AO Comments 1 6 AO1b AO1a AO2a Indicative Chemistry content Stage 1: Formation of productNucleophilic attackPlanar carbonyl groupH attacks from either side (stated or drawn) Stage 2: Nature of productProduct of step 1 shownThis exists in two chiral forms (stated orEqual amounts of each enantiomer/racemic drawn) mixture formed Stage 3: Optical activityOptical isomers/enantiomers rotate the plane of polarised light equally in opposite directionsWith a racemic/equal mixture the effects cancel 19 of 20 Question 11.1 11.2 Level 2 34 marks Level 1 12 marks Level 0 0 marks CH3CH2COCH3 + 2[H] CH3CH2CH(OH)CH3 This question is marked using levels of response. Refer to the Mark Scheme Instructions for Examiners for guidance on how to mark this question. Level 3 56 marks All stages are covered and the explanation of each stage is generally correct and virtually complete. Answer is communicated coherently and shows a logical progression from stage 1 to stage 2 then stage 3. All stages are covered but the explanation of each stage may be incomplete or may contain inaccuracies OR two stages are covered and the explanations are generally correct and virtually complete. Answer is mainly coherent and shows progression from stage 1 to stage 3. Two stages are covered but the explanation of each stage may be incomplete or may contain inaccuracies, OR only one stage is covered but the explanation is generally correct and virtually complete. Answer includes isolated statements but these are not presented in a logical order or show confused reasoning. Insufficient correct chemistry to gain a mark.<br />](https://learnah.org/wp-content/uploads/2018/08/Specimen_MS_-_Paper_2_AQA_Chemistry_A-Level_11-1.jpg)