Prelim Paper 1 QP (with suggested solutions)_ACJC H2 Chem

1 © ACJC 2025 9729/01/Prelim/2025 [Turn over Anglo-Chinese Junior College JC2 Preliminary Examination Higher 2 CHEMISTRY Paper 1 Multiple Choice Additional Materials: Multiple Choice Answer Sheet Data Booklet 9729/01 17 September 2025 1 hour READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. Write your name and index number on the Answer Sheet in the spaces provided unless this has been done for you. There are thirty questions in this section. 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. This document consists of 16 printed pages.

2 © ACJC 2025 9729/01/Prelim/2025 [Turn over 1 The most common oxidation state of americium, Am, in aqueous solution is +3. Recently, Cu3+ has been shown to quantitatively oxidise Am3+(aq) in dilute HNO3, while itself is reduced to Cu2+. In an experiment, 20.0 cm 3 of 0.0120 mol dm –3 Am3+(aq) was found to require 24.00 cm3 of 0.0300 mol dm–3 Cu3+ for complete oxidation. What is the formula of the americium-containing species formed? A Am2O22+ B AmO22+ C AmO2+ D AmO+ n(electrons) = n(Cu3+) = 7.20 X 10-4 change in oxidation state of Am = (7.20 X 10-4) / (20.0 X 0.0120 / 1000) = +3 Initial oxidation state of Am = +3 +3 = +6 Correct option is AmO22+ 2 Use of the Data Booklet is relevant to this question. The table shows the fifth, sixth, seventh, eighth, ninth and tenth ionisation energies of an element (Z ≤ 20) in the Periodic Table. 5th 6th 7th 8th 9th 10th ionisation energy / kJ mol–1 7975 9590 11343 14944 16964 48610 What can be inferred about the element from the above data? A It is in the third period of the Periodic Table. B It is in Group 2 of the Periodic Table. C It is likely to form an ionic compound when reacted with oxygen. D Its 6th and 7th electrons are removed from different subshells. C: There is a large electronegativity difference between the Group 1 element and oxygen (Group 16). Hence, the compound formed will be ionic in nature. A: There is insufficient data to conclude that the element lies in the third period. Since Z ≤ 20, this Group 1 element can be in the fourth period. B: The largest increase in successive ionisation energies (IE) occur between 9th and 10th IE. This implies that the 10th electron is removed from an inner shell. Since Z ≤ 20, only s and p subshells exists. Hence, each shell can only accommodate up to a maximum of 8 electrons. This would imply that the 2nd to 9th electro