NYJC 2021 H2 Chemistry 9729 P3

[Turn Over NANYANG JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME CLASS TUTOR’S NAME CHEMISTRY 9729/03 Paper 3 Free Response 14 September 2021 2 hours Candidates answer on the Question Paper. Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Write your name and class on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Answer all questions in the spaces provided on the Question Paper. If additional space is required, you should use the pages at the end of this booklet. The question number must be clearly shown. Section A Answer all questions. Section B Answer one question. A Data Booklet is provided. The use of an approved scientific calculator is expected, where appropriate. 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 1 /22 2 /18 3 /20 4 /20 5 /20 Total /80 This document consists of 31 printed pages..

2 H2 Chemistry 9729/03 NYJC J2/2021 PRELIM. Section A Answer all the questions in this section. 1 Phosgene, COCl2, is a colourless gas that has the odour of freshly cut hay. It is a major industrial chemical used to make plastics and pesticides. It is highly toxic and was used extensively during World War I as a choking agent. (a) (i) Draw a dot-and-cross diagram of the phosgene molecule. [1] (ii) The actual value of the Cl-C-Cl bond angle is 117 o. Using the principles of the VSEPR theory, x deduce the expected Cl-C-Cl bond angle. x compare the two values and suggest a reason for the discrepancy. [2] …………………………………………………………………………………………........... …………………………………………………………………………………………........... …………………………………………………………………………………………........... …………………………………………………………………………………………........... …………………………………………………………………………………………........... …………………………………………………………………………………………........... …………………………………………………………………………………………........... …………………………………………………………………………………………........... …………………………………………………………………………………………........... …………………………………………………………………………………………........... …………………………………………………………………………………………........... …………………………………………………………………………………………........... …………………………………………………………………………………………........... …………………………………………………………………………………………........... …………………………………………………………………………………………........... …………………………………………………………………………………………........... …………………………………………………………………………………………........... …………………………………………………………………………………………........... ………………………………