2024 TMJC H1 Chem Prelim P2 (Ans)

CANDIDATE NAME SUGGESTED ANSWERS CIVICS GROUP ______________________________________________________________________________ H1 CHEMISTRY 8873/02 Paper 2 Structured Questions 12 September 2024 2 hours Candidates answer on the Question Paper. Additional materials: Data Booklet ______________________________________________________________________________ READ THESE INSTRUCTIONS FIRST Write your name and civics group in the spaces provided at the top of this page. Write in dark blue or black pen on both sides of the paper. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Section A Answer all the questions. Section B 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. ________________________________________________________________________________________ This document consists of 25 printed pages and 1 blank page. Examiner’s Use Paper 1 MCQ / 30 Paper 2 Section A Q1 / 9 Q2 / 6 Q3 / 14 Q4 / 8 Q5 / 10 Q6 / 13 Section B Q7 / 20 Q8 / 20 / 80 Total / 100 Grade TAMPINES MERIDIAN JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATION

2 Tampines Meridian Junior College 2024 JC2 Preliminary Examination H1 Chemistry Section A Answer all the questions in this section in the spaces provided. 1 (a) Aluminium and boron are two elements of Group 13. (i) Complete the electronic configuration for Al and Al3+. Al: 1s2 ………………………………. Al3+: 1s2 ………………………………. [1] (ii) Atoms of elements are made up of the three subatomic particles: protons, electrons and neutrons, in varying numbers. Complete Table 1.1 for each subatomic particle of an atom of Al13 26 . Table 1.1 [1] (b) The compounds of aluminium and boron have many uses. Alumin ium oxide, Al2O3, is commonly used as a refractory material for lining furnaces while aluminium chloride, AlCl3, is an antiperspirant agent. Boron trichloride, BCl3, is used in the refining process of aluminium. (i) Draw the dot-and-cross diagrams for Al2O3 and AlCl3. [1] [1] [2] (ii) Briefly describe the bonding in AlCl3 in terms of the overlap of orbitals. ………………………………………………………………………………………………. …………………………………………………………………………………………… [1] atom number of protons number of neutrons number of unpaired electrons Al13 26 13 13 1 There are 3 single Al–Cl covalent bonds where the orbitals overlap head-on to form () bonds. [1] 2s22p63s23p1 2s22p6 [1] for both [1] for all three entries

3 Tampines Meridian Junior College 2024 JC2 Preliminary Examination H1 Chemistry [Turn over (iii) With reference to the Valence Shell Electron Pair Repulsion Theory , explain the shape and bond angle with respect to the B atom in BCl3. …………………………