XMS SEC 3 WA1 2022 MS

3 S3E 2022 WA1 Answers Section A [5 marks] 1 2 3 4 5 D A C C B Section B [30 marks] B1 (a) C (no mark) It has accepted 1 electron./The number of protons and electrons differ./The number of electrons is bigger than the number of protons. 1 (b) A and B are isotopes. Both have the same number of protons (17) but different number of neutrons (18 for A and 20 for B). 1 1 (c) correct outer shell electrons (1) correct charges (1) correct ratio of ions (1) 3 B2 (a) Any 6 points of: in steam, particles/molecules are far apart in water, particles/molecules are close together in steam more randomness in arrangement of particles/molecules in steam, particles/molecules are moving very fast in water, particles/molecules are moving slowly / sliding over each other in steam, the attractive forces between particles are very weak in water, the attractive forces between particles are strong NOTE: answer must show a comparison e.g. particles/molecules are further apart in steam (than in water) = 2 points, particles/molecules move faster in steam (than in water) = 2 points NOT: implication of particles ‘apart’ in liquids 3 (b)(i) boiling (NOT: evaporation) 1 (ii) B to C 1 A A D

4 B3 (a) number of electrons in outer shell gives the group number (1) number of shells (containing electrons) gives the period number (1) 2 (b) 54 e 82 n 56 p 1 1 1 (c)(i) 2.8 1 (ii) correct outer shell electrons (1) correct charges (1) correct ratio of ions (1) 3 B4(a) sum/number of protons and neutrons ALLOW: particles in the nucleus 1 (b) The h igher the nucleon (mass) number, the lower the speed ( or reverse argument) 1 (c) Argon has a nucleon (mass) number of 40, which is double that of neon (20) Average speed of argon particles is 400 ms -1, while average speed of neon particles is 550 ms-1. 550 / 2  400 (hence student’s statement is incorrect). 1 1 1 (d)(i) Anywhere on the right side of the tube HCl has a larger nucleon (mass) number than CH3NH2, and so diffuses (NOT: move) more slowly (and travels shorter distance). 1 1 1 (ii) Similarity: A white solid is formed in both experiments. / A white solid is formed nearer to HCl in both experiments. Difference: The white solid is formed more quickly in Experiment 2 than in Experiment 1 / A shorter time taken for the white solid to form in Experiment 2 than in Experiment 1. NOT: the gases diffuse faster / react more quickly (these are NOT observations) 1 1 3 O 2- Al 3+ 2