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Edexcel Jan 2015 (IAL) Paper 1 Q24
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![Question Number 24(a) Question Number 24(b) Question Number 24(c)(i) Mark Mark Mark Acceptable Answers Reject (Relative mass) (Relative charge) +1/1+ 1/1 Just + for proton charge Just neutral for neutron charge Justfor electron charge Zero /0 for mass of an electron (Sub- atomic particle) (proton) (neutron) (electron) 1/2000 to 1/1800 or negligible or 0.0005 to 0.00056 (1) for each correct row MAX (1) if only one COLUMN correct IGNORE any masses in g or kg IGNORE any charges in coulombs Acceptable Answers Reject Element(s) with the same number of protons Atoms with the same number of protons (1) IGNORE same number of electrons (but) different numbers of neutrons (1) IGNORE References to atomic number / mass number / nucleons / JUST atoms of the same element Acceptable Answers Reject Just electrons / Highly-charged electrons Electron gun / high-speed electrons / high-energy electrons / fast-moving electrons / bombardment with electrons (1) Knock-out / remove electron(s) (1) IGNORE References to ionizing / forming ions / just equations such as Rb(g)Rb+(g) + e / other stages in the process of mass spectrometry WCH0101 1501<br />
Question Number 24(c)(ii) Question Number 24(d) Reject Mark Acceptable Answers [FIRST, check the answer on the answer line IF answer = 85.6 award (3) marks] 1st mark: 85 x 2.5 + 87 x 1 OR 85 x 71.4 + 87 x 28.6 (1) 2nd mark: 3.5 (can 7 if ratio given as 5:2) OR 100 ALLOW TE using incorrect % abundances or ratios (1) 3rd markstand alone for correct rounding (TE only if value calculated is between 85 and 87) (= 85.57, but accurate answer depends on rounding) Final answer rounded to 85.6 (ie 1 dp) Ignore units even if incorrect. (1) NOTE 85.5 without working scores (0) Mark Acceptable Answers Reject (Left-hand box) Delocalised electron(s) BOTH these words needed (1) (Right-hand box) Positive ion(s) / cation(s) / Rb+ ALLOW metal ion(s) (1) Just electrons Negatively- charged ions nuclei / nucleus / positive atoms positively-charged lattice (Total for Question 24 = 12 marks) WCH0101 1501<br />](https://learnah.org/wp-content/uploads/2018/08/January_2015_IAL_MS_-_Unit_1_Edexcel_Chemistry_A-level_24-0.jpg)
