TMJC_2025_H1 Chem_P1 _Answer

___________________________________________________________________ H1 CHEMISTRY 8873/01 Paper 1 Multiple Choice 25 September 2025 1 hour Additional materials: Multiple Choice Answer Sheet Data Booklet _________________________________________________________________________ READ THESE INSTRUCTIONS FIRST Write in soft pencil. There are thirty questions in this section. Answer all questions. For each question, there are four possible answers labelled A, B, C and D. Choose the one you consider correct and record your choice in soft pencil on the separate Answer Sheet. Read very carefully the instructions on the use of Answer Sheet. You are advised to fill in the Answer Sheet as you go along; no additional time will be given for the transfer of answers once the examination has ended. 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 12 printed pages. Use of Answer Sheet Ensure you have written your name, class, date and subject on the Answer Sheet. Shade the last four digits of your centre/index number on the Multiple Choice Answer Sheet. (e.g. if your centre/index number is 30541234, shade 1234). Use a 2B pencil to shade your answers on the Answer Sheet; erase any mistakes cleanly. Multiple shaded answers to a question will not be accepted. TAMPINES MERIDIAN JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATION

2 Tampines Meridian Junior College 2025 JC2 Preliminary Examination H1 Chemistry 2 Atoms of elements from hydrogen to zinc have specific electronic arrangements. Which statement is correct? A The shell with principal quantum number 3 can hold a maximum of 8 electrons. B The electrons always occupy the highest energy orbitals available. C The order of filling the orbitals is 1s, 2s, 2p, 3s, 3p, 3d, 4s. D In some atoms, electrons occupy the fourth shell even though the third shell is not full. Answer: D Transition elements to fill 4s subshell before 3d. Examples include Sc: [Ar]3d 14s2 Ti: [Ar]3d 24s2 1 The relative atomic mass of antimony, which consist of the isotopes 121Sb and 123Sb, is 121.8. Calculate the percentage of 123Sb in the isotopic mixture. A 40% B 45% C 50% D 60% Answer: A Let the percentage of 123Sb in the isotopic mixture be x% 𝑥 100 123 + 100 − 𝑥 100 121 = 121.8 123x -121x = 80 x = 40% 3 Elements E and F have the following successive ionisation energies in kJ mol−1. 1st 2nd 3rd 4th 5th 6th 7th E 580 1800 2700 11600 14800 18400 23300 F 1310 3400 5300 7500 11000 13300 20300 What could be the formula of the compound formed by these two elements? A EF3 B E2F3 C E3F2 D E4F3 Answer: B Element E is from Group 13: largest IE difference between 3 r