VS 2020 O Level Pure Chemistry P1+P2 Answer Scheme

2020 Answer1 Victoria School2020 Chemistry O Levels / 6092Suggested Answer Key PAPER 1Q1Q2Q3Q4Q5Q6Q7Q8Q9Q10Q11Q12Q13Q14Q15Q16Q17Q18Q19Q20DDAABCBAABAACDBCBDCCQ21Q22Q23Q24Q25Q26Q27Q28Q29Q30Q31Q32Q33Q34Q35Q36Q37Q38Q39Q40CBBADABDDBDCDCDDABABPAPER 2 (SECTION A)QuestionAnswerMarkA1aicalcium hydroxide1aiihydrogen AND iron 1aiiigraphite1aivethanol1avgraphite1avihydrogen AND graphite 1bTrue, True, False, False1A2aUnder the conditions of the car engine, the nitrogen and oxygen molecules gain thermal energy and thus gain kinetic 1

2020 Answer2 energy and move faster. In addition, there are more reactant particles that have the minimum energy for reaction to occur. There are more collisions between the reactant particles, hence increasing the frequency of effective collisions between reacting particles. Thus, rate of reaction increases. 11biequation 1: 2NO + O2 → 2NO2equation 2: 3NO2 + H2O → 2HNO3 + NO11biisulfur dioxide1A3a electron anion (metal) cation cation1 for metal1 for ionicbMetals have a sea of mobile (delocalised valence) electrons that are able to move and carry charge.Ionic compounds are able to conduct electricity in molten and aqueous states as the giant ionic structure collapses and the ions are able to move and carry charge. 11ciIn pure iron, the iron atoms are of the same size and arranged in regular rows. Hence, the layers of iron atoms can slide over each other easily with lesser force, resulting in pure iron being malleable and ductile.In mild steel, the addition of different sized carbon atoms disrupt the regular/orderly arrangement of the metal lattice. Hence, the layers of iron atoms can no longer slide over each other as easily when a force is applied, resulting in iron alloy being stronger and more brittle.11ciiThe table shows that iron atoms have a larger atomic radius than the carbon atoms but are shown in the diagram to be smaller. 2

2020 Answer3 ORThe table shows that there are 3 types of elements in mild steel, but only iron and carbon are shown in the diagram.ORThe percentage by mass of carbon is the diagram is approximately 3.5% but it is stated in the table to be only 0.25%.CHOOSE ANY 2 ANSWERSA4aThe iron can should be made the cathode/connected to the negative terminal of the battery, while a piece of tin should be made the anode/connected to the positive terminal of the battery. Both items should be dipped into the electrolyte which is an aqueous solution containing Sn2+ ions/ aqueous tin(II) nitrate.111bSn(s) + 2H+(aq) → Sn2+(aq) + H2 (g) 1ciPoly(ethene) does not react with dilute acids found in food/is non-biodegradable.1ciiMacromolecule: A large molecule made up of many small molecules succesively joined together. Addition polymerisation: The successive additon of monomers that are joined together to form only one (large) product without any loss of atoms or molecules. 11A5aThe melting point of silicon dioxide is higher than carb