INTERNATIONAL GCSE CHEMISTRY 9202/2 Paper 2 Mark scheme November 2021 Version: 1.0 Final Mark Scheme

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Marking points 3.1 Marking of lists This applies to questions requiring a set number of responses, but for which students have provided extra responses. The general principle to be followed in such... a situation is that ‘right + wrong = wrong’. Each error / contradiction negates each correct response. So, if the number of errors / contradictions equals or exceeds the number of marks available for the question, no marks can be awarded. However, responses considered to be neutral (indicated as * in example 1) are not penalised.MARK SCHEME – INTERNATIONAL GCSE CHEMISTRY – 9202/2 – NOVEMBER 2021 5 Example 1: What is the pH of an acidic solution? [1 mark] Student Response Marks awarded 1 green, 5 0 2 red*, 5 1 3 red*, 8 0 Example 2: Name two planets in the solar system. [2 marks] Student Response Marks awarded 1 Neptune, Mars, Moon 1 2 Neptune, Sun, Mars, Moon 0 3.2 Use of chemical symbols / formulae If a student writes a chemical symbol / formula instead of a required chemical name, full credit can be given if the symbol / formula is correct and if, in the context of the question, such action is appropriate. 3.3 Marking procedure for calculations Marks should be awarded for each stage of the calculation completed correctly, as students are instructed to show their working. Full marks can, however, be given for a correct numerical answer, without any working shown. 3.4 Interpretation of ‘it’ Answers using the word ‘it’ should be given credit only if it is clear that the ‘it’ refers to the correct subject. 3.5 Errors carried forward Any error in the answers to a structured question should be penalised once only. Papers should be constructed in such a way that the number of times errors can be carried forward is kept to a minimum. Allowances for errors carried forward are most likely to be restricted to calculation questions and should be shown by the abbreviation ecf in the marking scheme. 3.6 Phonetic spelling The phonetic spelling of correct scientific terminology should be credited unless there is a possible confusion with another technical term.MARK SCHEME – INTERNATIONAL GCSE CHEMISTRY – 9202/2 – NOVEMBER 2021 6 3.7 Brackets (…) are used to indicate information which is not essential for the mark to be awarded but is included to help the examiner identify the sense of the answer required. 3.8 Allow In the mark scheme additional information, ‘allow’ is used to indicate creditworthy alternative answers. 3.9 Ignore ‘Ignore’ is used when the information given is irrelevant to the question or not enough to gain the marking point. Any further correct amplification could gain the marking point. 3.10 Do not accept ‘Do not accept’ means that this is a wrong answer which, even if the correct answer is given as well, will still mean that the mark is not awarded.MARK SCHEME – INTERNATIONAL GCSE CHEMISTRY – 9202/2 – NOVEMBER 2021 7 Question 1 Question Answers Extra information Mark AO/ Spec. Ref. 01.1 model A has no protons model A has no neutrons model A has no nucleus model A does not have electrons in shells / energy levels allow converse for model B 1 1 1 1 AO1 AO3 × 3 3.1.2c i Question Answers Extra information Mark AO/ Spec. Ref. 01.2 4 1 AO2 3.1.2a Question Answers Extra information Mark AO/ Spec. Ref. 01.3 (protons =) 17 (electrons =) 17 (neutrons =) 18 1 1 1 AO2 3.1.2f h Question Answers Extra information Mark AO/ Spec. Ref. 01.4 neutrons 1 AO1 3.1.2g [Show More]

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