2025 RI H1Chem Prelims P1 Questions

RAFFLES INSTITUTION 2025 YEAR 6 PRELIMINARY EXAMINATION Higher 1 CHEMISTRY 8873 / 01 Paper 1 Multiple Choice 26 September 2025 1 hour Additional Materials: Multiple Choice Answer Sheet Data Booklet READ THESE INSTRUCTIONS FIRST Do not open this question booklet until you are told to do so. Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. Write your name, class and index number in the spaces provided on the Answer Sheet. 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 the question booklet. The use of an approved scientific calculator is expected where appropriate. This document consists of 12 printed pages.

2 © Raffles Institution 2025 8873/01/S/25 [Turn Over 1 Which statement about 32S2− and 34S is correct? A Both have the same number of protons. B Both have the same number of electrons. C Both have the same number of neutrons. D Both have the same mass number. 2 Which statement about orbitals and electrons in an argon atom is correct? 1 The shell with principal quantum number 3 has no unpaired electrons. 2 The valence electronic configuration of an isolated atom is 3s2 3p6 3d10. 3 The 2p orbitals have different energies but same shape. A 1 and 2 B 1 only C 1 and 3 D 3 only 3 Use of the Data Booklet is relevant to this question. Substances exhibit magnetic behaviour based on the presence or absence of unpaired electrons. Paramagnetic species contain one or more unpaired electrons, making them slightly attracted to an external magnetic field. Diamagnetic species have all their electrons paired, causing them to be weakly repelled by a magnetic field. Which of the following species is diamagnetic? A Ti2+ B Zn2+ C Cu2+ D Fe2+ 4 Which species contains only covalent and dative bonds within itself? A Al2O3 B SO3 C NH4Cl D H3O+

3 © Raffles Institution 2025 8873/01/S/25 [Turn Over 5 The reactivity of halogen derivatives can be observed in the following reaction. CH3CH2X + OH− ⎯→ CH3CH2OH + X− (X = Cl or Br) Which statement explains why the reaction takes place more rapidly for bromoethane than for chloroethane? 1 Permanent dipole-per