2024 H1 Chem JC2 Prelim P2 (Q&A)_JPJC

© Jurong Pioneer Junior College [Turn over Name:____________________________________ Class:_____________ JURONG PIONEER JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATION 2024 CHEMISTRY 8873/02 Higher 1 2024 Paper 2 2 hours Additional materials: Data Booklet READ THESE INSTRUCTIONS FIRST Write your name, class and exam index number on all the work you hand in. Write in dark blue or black pen on both sides of the paper. You may use a HB pencil for any diagrams, graphs. Do not use staples, paper clips, glue or correction fluid. Section A (60 marks) Answer all the questions. Section B (20 marks) Answer one question. The use of an approved scientific calculator is expected, where appropriate. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use Section A 1 6 2 17 3 6 4 9 5 12 6 5 7 5 Section B 8 20 9 20 Penalty (delete accordingly) Missing/wrong units in final answer –1 / NA Total 80 This document consists of 24 printed pages and 4 blank pages.

2 © Jurong Pioneer Junior College 8873/02/J2 PRELIMINARY EXAMINATION /2024 Section A Answer all the questions in this section, in the spaces provided. 1 The oxygen family is also called the chalcogens. It consists of the elements found in Group 16 of the periodic table, oxygen, sulfur, selenium, tellurium and polonium. Chalcogen can be found in nature in both free and combined states. For Examiner’s Use (a) Complete the diagram to show the arrangement of electrons in the orbitals of a sulfur atom. 1s 2s 2p 3s 3p [1] 1s 2s 2p 3s 3p (b) State and explain the general trend in the first ionisation energy across Period 3 elements. Explain why sulfur does not follow this general trend. Across the Period, the nuclear charge increases while the shielding effect by inner shell electrons is relatively constant (since there is same number of quantum shells with electrons). Hence, the nuclear attraction on the outermost electrons increases and the 1st IE generally increases across the Period. The inter–electronic repulsion between the paired 3p electron of S makes it easier to remove one of the paired 3p electrons than the unpaired 3p electron of P which do not experience such repulsion. Hence, the 1st IE of S is lower than that of P. [2] (c) Selenium burns in air with a blue flame to form white solid SeO 2. When SeO2 reacts with water it forms H2SeO3(aq) which has a pH of less than 7. (i) Choose two oxides, each containing a different Period 3 element, which behave in a similar way to SeO2 when they are added to water. Write equation for the reaction of each oxides with water. SO2 + H2O → H2SO3 or SO3 + H2O → H2SO4 P4O6 + 6H2O → 4H3PO3 or P4O10 +