2024 Prelims ACJC H2 Chem P1 (Ans)

This document consists of 19 printed pages. Anglo-Chinese Junior College JC2 Preliminary Examination Higher 2 CHEMISTRY Paper 1 Multiple Choice Additional Materials: Multiple Choice Answer Sheet Data Booklet 9729/01 9 September 2024 1 hour READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. Write your name, Centre number and index number on the Answer Sheet in the spaces provided unless this has been done for you. There are thirty questions on this paper. Answer all questions. For each question there are four possible answers A, B, C and D. Choose the one you consider correct and record your choice in soft pencil on the separate Answer Sheet. Read the instructions on the Answer Sheet very carefully. Each correct answer will score one mark. A mark will not be deducted for a wrong answer. Any rough working should be done in this booklet. The use of an approved scientific calculator is expected, where appropriate.

2 © ACJC2024 9729/Preliminary Examinations/2024 [Turn over Solutions 2 0.01 mol of an unknown ion G2+ required 17.25 cm3 of 0.23 mol dm-3 acidified KMnO4 to reach the end-point. What is the final oxidation state of element G? A +3 B +4 C +5 D +6 MnO4− + 8H+ + 5e− → Mn2+ + 4H2O Amt of MnO4− = 0.01725 x 0.23 = 3.968 x 10−3 mol Amt of e− = 3.968 x 10−3 x 5 = 1.984 x 10−2 mol 1.984 x 10−2 / 0.01 = 1.98 ≈ 2 1 mol of X2+ loses 2 mol of e−, so final O.S of X is +4. 1 D 6 B 11 C 16 A 21 D 26 B 2 B 7 A 12 C 17 D 22 C 27 B 3 B 8 D 13 D 18 D 23 B 28 B 4 C 9 A 14 A 19 C 24 C 29 B 5 D 10 B 15 D 20 A 25 B 30 D 1 The incomplete combustion of a gaseous hydrocarbon produced 80 cm 3 of carbon dioxide, 40 cm3 of carbon monoxide and 160 cm3 of water vapour. What volume of oxygen was used for combustion of the hydrocarbon? A 40 cm3 B 80 cm3 C 160 cm3 D 180 cm3 CxHy + 9 2 O2 → 2CO2 + CO + 4H2O 40 80 40 160 Comparing volume ratio of gases, 40 × 9 2 = 180 cm3

3 © ACJC2024 9729/Preliminary Examinations/2024 [Turn over 3 Which ion will be deflected the most in an applied electric field? A 79Br+ B 81Br2+ C 81Br+ D 82Br2+ Angle of deflection is directly proportional to charge/mass ratio. 81Br2+ has the largest charge/mass ratio, so it will be deflected the most in an electric field. 4 An unstable ion has • a nucleon number of 219, • 51 more neutrons than electrons • an atomic number of 84, 85, 86, or 87. What could this ion be? A Po2+ B At3+ C Rn4+ D Fr5+ Po2+ At3+ Rn4+ Fr5+ number of protons 84 85 86 87 number of electrons 82 82 82 82 number of neutrons 133 133 133 133 nucleon number 217 218 219 220 5 Which species contains two 𝜋 bonds? 1 BF3NH3 2 CH2CHCH2CH3 3 CH2CHC