![]() ![]() melting point decreases as atomic radius increases.OCR Gateway Science, GCE Chemistry, Unit B742: Specimen paper (2012) Chemistry modules C4, C5, C6 (Higher Tier) Reveal answer Include in your answer predictions for the atomic radius and melting point of rubidium. Elementĭescribe and explain the relationship between atomic radii and melting points of the elements in group 1. It shows some information about the elements in group 1. This question is about group 1 elements such as sodium and rubidium. ![]() bromide (ions) give a cream precipitate with silver nitrate - allow solid instead of precipitate.iron(II) (ions) give a green precipitate with sodium hydroxide.because chloride ions give a white precipitate with silver nitrate.because sodium gives a yellow flame test colour.Mark allowed for KCl + AgNO 3 → AgCl + KNO 3. Mark awarded for correct formulae or mix of words and formulae. potassium chloride + silver nitrate → silver chloride + potassium nitrate.OCR Gateway Science, GCE Chemistry, Unit B742: June 2016 Chemistry modules C4, C5, C6 (Foundation Tier) Identify the unknown compounds A and B and explain your answers. Potassium chloride reacts with silver nitrate to make silver chloride and potassium nitrate. These are the tests that Jed does on solutions of the compounds: Jed is testing potassium chloride and some unknown compounds. ignore solid/colour of metal/heavy/light not properties opposite to list above/magnetic.also allow does not react with water/does not rust.idea of being malleable so it can be made into sheets.idea of strong to be able to be used as a wing so can withstand forces.idea of low density since it is used for an aeroplane and will require less force to lift.physical properties - hard, good thermal conductor, good electrical conductor, lustrous, sonorous, high melting point, high boiling point, high tensile strengthĮxamples of relating properties to use in aeroplanes:.link that transition elements are metals.identification as a transition element using its position in the periodic table.OCR Gateway Science, GCE Chemistry, Unit B742: Specimen paper (2012) Chemistry modules C4, C5, C6 (Foundation Tier) Reveal answer Predict four physical properties of titanium.Įxplain why you make your predictions and relate the properties to the use of titanium in making aeroplane wings. Titanium, Ti, atomic number 22, is used to make the wings of some aeroplanes. You do not usually need to include all of them to gain six marks, but you do need to write in full sentences, linking them logically and clearly. The answers shown here give marking points as bullet points. Remember that the topics covered in the first paper are assumed knowledge for the second paper, so questions in the second paper may need knowledge and understanding of those topics too. For example, a question about fertilisers could include ideas about covalent substances, acids and alkalis, chemical calculations and effects on the environment. This means they bring together ideas from two or more topics. Six-mark questions may be synoptic questions. evaluate - you must review information, including identifying strengths and weaknesses, and make a supported conclusion.devise - you must plan or invent a procedure using your scientific knowledge and understanding.explain - you must give reasons or explanations.describe - you need to give an account but no reason.You are likely to see command words such as: maintain a sustained line of reasoning, rather than getting lost or bogged down.write clearly, linking ideas in a logical way.use appropriate scientific words and terms.support explanations using scientific knowledge and understanding.Six-mark questions are marked using a levels-based mark scheme because they are open ended. It is wise to plan your answer rather than rushing straight into it, otherwise you may stray away from the key points. These require longer answers than the structured questions with fewer marks. Six-mark questions are extended open response questions. ![]()
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