2020 JPJC Prelim Paper 2 (Question Paper)

1  Jurong Pioneer Junior College 9729/02/J2 PRELIMINARY EXAM/2020 [Turn Over NAME CLASS 19S JURONG PIONEER JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATION 2020 CHEMISTRY 9729/02 Higher 2 Paper 2 Structured Questions 17 September 2020 2 hours Candidates answer on the Question Paper. 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. Answer all questions in the spaces provided on the Question Paper. The use of an approved scientific calculator is expected, where appropriate. A Data Booklet is provided. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use Paper Question Mark 2 1 13 2 9 3 14 4 12 5 6 6 21 Penalty (delete accordingly) Lack 3sf in final ans –1 / NA Missing/wrong units in final ans –1 / NA Total 75 This document consists of 21 printed pages.

2  Jurong Pioneer Junior College 9729/02/J2 PRELIMINARY EXAM/2020 Answer all the questions in the spaces provided. 1 (a) The following graph below shows the second ionisation energies of Period 3 elements with consecutive proton number. For Examiner’s Use (i) Explain why the second ionisation energy generally increases from B to H. ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… [2] (ii) Which of the above elements, A to H, is aluminium? ………………………………………………………………………………… [1] (iii) Explain the following:  big drop in second ionisation energy from A to B  slight drop in second ionisation energy from C to D ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… ………………………………………………………………………………… [2] 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 5,000 C D E F G H A B 2nd Ionisation Energy/ kJ mol–1

3  Jurong Pioneer Junior College 9729/02/J2 PRELIMINARY EXAM/2020 [Turn Over (b) Among the elements of Group 14, those towards the top, carbon to germanium, have very different properties from th ose at the bottom, tin and lead. For example, the melting points show a marked change after germanium. element C Si Ge Sn Pb mp / C >3550 1410 937 232 327 Carbon, silicon and germanium each form a solid with the same type of structure. (i) Explain why the melting points of these elements decrease from ca