2020 SNGS Y4IP EOY Answers

SNGS Mark scheme for Year 4 IP EOY 2020 Paper 1 Answers to Section A: Circle the most appropriate answer to each question. 1 A 11 D 2 B 12 A 3 C 13 A 4 B 14 B 5 A 15 D 6 D 16 D 7 C 17 C 8 B 18 D 9 A 19 C 10 D 20 A 21 D 31 B 22 C 32 B 23 C 33 C 24 B 34 D 25 C 35 B 26 D 36 A 27 C 37 D 28 D 38 D 29 A 39 B 30 D 40 D

2 SNGS Mark scheme for Year 4 IP EOY 2020 Paper 2 Section A (50 marks) A1 a Manganese(IV) oxide OR Nickel [1] b Ammonium chloride [1] c Calcium carbonate [1] d Lead(II) hydroxide [1] e Aluminium sulfate [1] f Ammonium chloride OR Iodine [1] A2 a Y [1] b Flat, horizontal line drawn at 55 °C Flat, horizontal line drawn at 80 °C Vertical lines at other parts of the graph Start and end at the given temp range [1] [1] c 4/6 = 0.67 Not in 2 dp: -1/2 m [1] d Yes, substance Y and the toxic dye have the same Rf value. [1]

3 e Pencil lead is insoluble in water / the solvent, hence it will not be separated together with the toxic dye and interfere with the results OR Pen ink is soluble in water / the solvent, hence it will be separated together with the toxic dye and interfere with the results [0.5] [0.5] A3 a Structure V [1] b Structure III [1] c Structure I and II [1] d Molecules Far apart, randomly arranged High speed in all directions [1] [0.5] [0.5] e Has a giant ionic structure In the solid state, there are strong electrostatic forces of attraction between oppositely charged ions Ions can only vibrate about fixed positions No mobile ions to conduct electricity [0.5] [0.5] [0.5] [0.5] A4 a Use acidified aqueous potassium manganate(VII) missing aqueous/solution or (VII) or wrong spelling: minus ½ Turns it from purple to colourless [1] [0.5] [0.5] b Cu2S is reduced as The oxidation state of copper decreased from +1 in Cu2S to 0 in Cu Cu2S is also oxidised as The oxidation state of sulfur increased from -2 in Cu2S to +4 in SO2 [0.5] [0.5] [0.5] [0.5] [0.5] [0.5] c CaCO3 + SO2 → CaSO3 + CO2 [1m] OR SO2 + H2O → H2SO3 CaCO3 + H2SO3 → CaSO3 + CO2 + H2O [award 1/2 m if any one equation above is balanced & correct] Wrong formula = 0 m [1] A5 a Increases [1] b Number of electron shells / atomic radius / size increases down the group distance between sea of delocalized electrons and positive ion increases Electrostatic forces of attraction decreases Less energy required [0.5] [0.5] [0.5] [0.5]

4 c Effervescence (of a colourless, odourless gas) is observed. Gas extinguished lighted splint with a pop sound [1] [1] d Down Group II, the metals/elements become more reactive. Hence their (metal) carbonates become more thermally stable If student did not