2025 H2 Chem Prelim P1 Worked Solution_CJC

1 9729/01 CJC JC2 Preliminary Examination 2025 [Turn over CANDIDATE NAME CLASS 2T CHEMISTRY 9729/01 Paper 1 Multiple Choice 18 September 2025 1 hour Additional Materials: Multiple Choice Answer Sheet Data Booklet READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. Write your name, class and NRIC/FIN number on the Answer Sheet in the spaces provided. 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. This document consists of 28 printed pages. WORKED SOLUTIONS Catholic Junior College JC 2 Preliminary Examinations Higher 2

2 9729/01 CJC JC2 Preliminary Examination 2025 1 The relative abundances of all the isotopes present in a sample of zirconium are shown. What is the relative atomic mass of zirconium calculated from these data? A 91.1 B 91.3 C 91.6 D 93.1 2 In the interhalogen compound ICl, there is a single polar covalent bond. Which of the following statement(s) helps to explain the polarity of the I–Cl covalent bond? 1 Cl is more electronegative than I. 2 The outer shell electronic configuration of both elements is s2 p6. 3 The outer shell electrons are more shielded from nuclear charge in I than they are in Cl. A 1, 2 and 3 B 1 and 2 C 1 and 3 D 1 only Topic: Atomic Structure Ar of Zr = 51.5(90)+11.2(91)+17.1(92)+17.4(94)+2.8(96) 100 = 91.3 Answer: B Topic: Chemical Bonding Polarity of a covalent bond depends on the electronegativity difference between two atoms. Electronegativity is a measure of the ability of an atom to attract the bonding electrons. Option 1: True; Cl is more electronegative than I. Option 2: True but does not explain why the bond is polar. Option 3: True; hence the attraction exerted by the nucleus of I on the shared pair of electrons is weaker than that of Cl. Answer: C 90 91 92 93 94 95 96 51.5 11.2 17.1 17.4 2.8 Mass of isotope relative abundance

3 9729/01 CJC JC2 Preliminary Examination 2025 [Turn over 3 In which pairs of compounds does the first molecule have a smaller bond angle than that in the second molecule? 1 NF3 CCl4 2 H2S H2O 3 SF6 CS2 A 1, 2 and 3 B 1 and 2 C 2 and 3 D 3 only 4 The table shows the boiling point of three alcohols. boiling point / °C pentan-1-ol 138 2-met