H GCSE (9 1) Combined Science (Chemistry) A (Gateway Science) J250/09 Paper 9, C1-C3 and CS7 (PAGs C1-C5) (Higher Tier) Year 11 Test MARK SCHEME Duration: 1 hour 10 minutes MAXIMUM MARK 60 This document consists of 16 pages OCR 2017
MARKING INSTRUCTIONS PREPARATION FOR MARKING RM ASSESSOR 1. Make sure that you have accessed and completed the relevant training packages for on-screen marking: RM Assessor Online Training; OCR Essential Guide to Marking. 2. Make sure that you have read and understood the mark scheme and the question paper for this unit. These are available in RM Assessor. 3. Log-in to RM Assessor and mark the required number of practice responses ( scripts ) and the required number of standardisation responses. MARKING 1. Mark strictly to the mark scheme. 2. Marks awarded must relate directly to the marking criteria. 3. The schedule of dates is very important. It is essential that you meet the RM Assessor 50% and 100% (traditional 50% Batch 1 and 100% Batch 2) deadlines. If you experience problems, you must contact your Team Leader (Supervisor) without delay. 4. If you are in any doubt about applying the mark scheme, consult your Team Leader by telephone, email or via the RM Assessor messaging system. 2
5. Work crossed out: a. where a candidate crosses out an answer and provides an alternative response, the crossed out response is not marked and gains no marks b. if a candidate crosses out an answer to a whole question and makes no second attempt, and if the inclusion of the answer does not cause a rubric infringement, the assessor should attempt to mark the crossed out answer and award marks appropriately. 6. Always check the pages (and additional objects if present) at the end of the response in case any answers have been continued there. If the candidate has continued an answer there then add a tick to confirm that the work has been seen. 7. There is a NR (No Response) option. Award NR (No Response) - if there is nothing written at all in the answer space - OR if there is a comment which does not in any way relate to the question (e.g. can t do, don t know ) - OR if there is a mark (e.g. a dash, a question mark) which isn t an attempt at the question. Note: Award 0 marks for an attempt that earns no credit (including copying out the question). 8. The RM Assessor comments box is used by your Team Leader to explain the marking of the practice responses. Please refer to these comments when checking your practice responses. Do not use the comments box for any other reason. If you have any questions or comments for your Team Leader, use the phone, the RM Assessor messaging system, or email. 9. Assistant Examiners will send a brief report on the performance of candidates to their Team Leader (Supervisor) via email by the end of the marking period. The report should contain notes on particular strengths displayed as well as common errors or weaknesses. Constructive criticism of the question paper/mark scheme is also appreciated. 3
10. For answers marked by levels of response: Read through the whole answer from start to finish, using the Level descriptors to help you decide whether it is a strong or weak answer. The indicative scientific content in the Guidance column indicates the expected parameters for candidates answers, but be prepared to recognise and credit unexpected approaches where they show relevance. Using a best-fit approach based on the skills and science content evidenced within the answer, first decide which set of level descriptors, Level 1, Level 2 or Level 3, best describes the overall quality of the answer. Once the level is located, award the higher or lower mark: The higher mark should be awarded where the level descriptor has been evidenced and all aspects of the communication statement (in italics) have been met. The lower mark should be awarded where the level descriptor has been evidenced but aspects of the communication statement (in italics) are missing. In summary: The skills and science content determine the level. The communication statement determines the mark within a level. Level of response questions on this paper are X and X 4
11. Annotations available in RM Assessor Annotation Meaning Correct response Incorrect response Omission mark Benefit of doubt given Contradiction Rounding error Error in number of significant figures Error carried forward Level 1 Level 2 Level 3 Benefit of doubt not given Noted but no credit given Ignore 5
12. Abbreviations, annotations and conventions used in the detailed Mark Scheme (to include abbreviations and subject-specific conventions). Annotation Meaning / alternative and acceptable answers for the same marking point DO NOT ALLOW IGNORE ALLOW Separates marking points Answers which are not worthy of credit Statements which are irrelevant Answers that can be accepted ( ) Words which are not essential to gain credit ECF AW ORA Underlined words must be present in answer to score a mark Error carried forward Alternative wording Or reverse argument 6
13. Subject-specific Marking Instructions INTRODUCTION Your first task as an Examiner is to become thoroughly familiar with the material on which the examination depends. This material includes: the specification, especially the assessment objectives the question paper the mark scheme. You should ensure that you have copies of these materials. You should ensure also that you are familiar with the administrative procedures related to the marking process. These are set out in the OCR booklet Instructions for Examiners. If you are examining for the first time, please read carefully Appendix 5 Introduction to Script Marking: Notes for New Examiners. Please ask for help or guidance whenever you need it. Your first point of contact is your Team Leader. 7
The breakdown of Assessment Objectives for GCSE (9-1) in Combined Science A: Assessment Objective AO1 AO1.1 AO1.2 AO2 AO2.1 AO2.2 AO3 AO3.1 AO3.1a AO3.1b AO3.2 AO3.2a AO3.2b AO3.3 AO3.3a AO3.3b Demonstrate knowledge and understanding of scientific ideas and scientific techniques and procedures. Demonstrate knowledge and understanding of scientific ideas. Demonstrate knowledge and understanding of scientific techniques and procedures. Apply knowledge and understanding of scientific ideas and scientific enquiry, techniques and procedures. Apply knowledge and understanding of scientific ideas. Apply knowledge and understanding of scientific enquiry, techniques and procedures. Analyse information and ideas to interpret and evaluate, make judgements and draw conclusions and develop and improve experimental procedures. Analyse information and ideas to interpret and evaluate. Analyse information and ideas to interpret. Analyse information and ideas to evaluate. Analyse information and ideas to make judgements and draw conclusions. Analyse information and ideas to make judgements. Analyse information and ideas to draw conclusions. Analyse information and ideas to develop and improve experimental procedures. Analyse information and ideas to develop experimental procedures. Analyse information and ideas to improve experimental procedures. 8
SECTION A Question Answer Marks AO element 1 D 1 AO1.1 2 C 1 AO1.1 3 D 1 AO2.1 4 B 1 AO1.2 5 C 1 AO2.2 6 B 1 AO2.2 7 C 1 AO1.2 8 B 1 AO2.2 9 C 1 AO1.2 10 A 1 AO2.2 Total 10 Guidance 9
SECTION B Question Answer Marks AO element 11 (a) (i) 62 1 AO1.1 Guidance (a) (ii) CH 3 O 1 AO1.1 (b) (i) Shared pair of electrons 2 AO1.1 Shared electrons pair of electrons (b) (ii) 4 electrons (in outer shell) 1 AO1.1 (b) (iii) 1 AO2.1 ALLOW OH 10
Question Answer Marks AO element Guidance 11 c Please refer to the marking instructions on page 4 of this mark scheme for guidance on how to mark this question. Level 3 (5 6 marks) Describes bonding and structure of all substances AND Explains melting points and conductivity in terms of structure and bonding. There is a well-developed line of reasoning which is clear and logically structured. The information presented is relevant and substantiated. Level 2 (3 4 marks) Describes bonding and structure of most substances AND Explains melting points OR conductivity in terms of structure and bonding. There is a line of reasoning with some structure. The information is relevant and supported by some evidence. Level 1 (1 2 marks) Describes bonding and structure of one substance OR Explains melting points OR conductivity in terms of structure and bonding. The information is basic and communicated in an unstructured way. The information is supported by limited evidence; relationship to the evidence may not be clear. 0 marks No response or no response worthy of credit. 6 AO1.1 3 AO3.2 3 AO1.1: Demonstrates knowledge and understanding of bonding in metals and polymers Bonding and structure in diamond and graphite: Covalent bonding. Diamond has 3D structure Graphite has layers Bonding and structure in aluminium: Cationic lattice. free/mobile electrons. AO3.2a: Analyse information and ideas to draw conclusions Good conductivity from moving electrons Graphite: electrons move between layers Aluminium: electrons move throughout structure High melting point linked to large amount of energy to break strong bonds Graphite and diamond: strong covalent bonds Aluminium: strong metallic bonds 11
Question Answer Marks AO element Guidance 12 (a) (Atoms of same element with) different numbers of 1 AO1.1 ALLOW different mass numbers/ neutrons different atomic masses (b) Protons Neutrons Electrons Na 23 11 12 11 0 K 40 19 21 18 1+ 1st row: Mass number AND electrons 2nd row: Protons AND neutrons BOTH elements: Na AND K 3 AO2.1 (c) (i) Electrons are transferred/lost from sodium to oxygen. 2 AO2.1 Each Na atom transfers/loses one electron. OR Each O atom gains/receives two electrons. (c) (ii) 2 AO1.2 NOTE: Circles for shells NOT required Brackets NOT required For O dot and cross, ALLOW 2 Na with 8 (or no) outer electrons AND O with dot-and-cross outermost octet ALLOW 12
Question Answer Marks + AND 2 charges AO element Guidance (c) (iii) 4Na(s) + O 2 (g) 2Na 2 O(s) Species Balance State symbols 3 AO2.1 3 (d) 3 2 AO1.2 ALLOW 3 Mg 3 N 2 AO2.2 13
Question Answer Marks AO element 13 (a) (i) Bubble through lime water 2 AO1.2 AO2.1 Turns milky OR cloudy OR white/grey precipitate (a) (ii) FIRST CHECK ANSWER ON THE ANSWER LINES 4 AO2.2 IF mass MgCO 3 = 1.68 g and mass HCl = 1.46 g award 4 marks Guidance Relative formula masses MgCO 3 = 84.3 AND HCl = 36.5 Mass of MgCO 3 0.02 84.3 = 1.68 g ALLOW ECF from incorrect M(MgCO 3 ) Mass of HCl 2 0.02 = 0.04 mol HCl ALLOW ECF from incorrect M(HCl) 0.04 36.5 = 1.46 g ALLOW ECF from incorrect mol of HCl (most likely 0.100 36.5 3.65 g) (b) Diagram showing: Suitable container AND (Filter) funnel AND Filter paper 5 AO3.3a 3 Suitable containers could include: (conical) flask/test tube/boiling tube Heat OR leave To remove/evaporate water AO2.2 2 ALLOW crystallise 14
AO Question Answer Marks element 14 (a) (i) Exothermic AND Temperature increases 2 AO1.2 Mark independently Guidance Energy is released OR given out (a) (ii) 3 Line added below reactants line AND HCl + NaOH added as reactants AND NaCl + H 2 O added as products Arrow labelled E from reactants to products Arrow labelled A from reactants to maximum energy (as in diagram) AO1.2 AO1.1 2 DO NOT ALLOW double-headed arrows (a) (iii) FIRST CHECK ANSWER ON THE ANSWER LINE IF answer = 2.4(0) g award 3 marks 3 Relative formula masses NaOH = 40 AO1.1 15
Question Answer Marks Mass of NaOH in 1 dm 3 2 40 = 80 g Mass of NaOH in 30 cm 3 0.0300 80 = 2.4(0) g AO element AO2.2 2 Guidance ALLOW ECF from incorrect M(NaOH) ALLOW ECF from incorrect mass NaOH in 1 dm 3 (a) (iv) The solutions release twice the energy 2 AO3.2b (b) The energy is spread out over twice the mass Gas at cathode: hydrogen OR H 2 H + attracted to cathode Gas at anode: oxygen OR O 2 OR Chlorine OR Cl OH attracted to cathode OR Cl- attracted to the cathode 4 AO3.1a AO3.1b AO3.1a AO3.1b 16