2021 YIJC Prelim P3 QP

©YIJC [Turn over YISHUN INNOVA JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME CG INDEX NO CHEMISTRY Paper 3 Free Response Candidates answer on the Question Paper Additional Materials: Data Booklet 9729/03 13 September 2021 2 hours This document consists of 34 printed pages. For Examiner’s Use Section A 1 /21 2 /25 3 /14 Section B 4 /20 5 /20 Penalty /80 READ THESE INSTRUCTIONS FIRST Write your name, class and 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 an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Section A Answer all questions. Section B Answer one question. 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.

2 ©YIJC Section A Answer all the questions in this section. 1 5-bromo-4-methyl-3-penten-2-ol can be made from 5 -bromo-4-methyl-3-penten-2-one in one step. The molecules are labelled as A and B respectively in Fig. 1.1. Fig. 1.1 (a) (i) State the total number of σ and π bonds in a molecule of A. [1] (ii) Describe the hybridisation of the orbitals and the bonds between the carbon atoms of the C=C double bond in A. [2] (iii) State the total possible number of stereoisomers that can be exhibited by B. [1] (iv) Sodium borohydride is used to reduce A to form B. Explain why only the ketone functional group in A undergoes reduction with sodium borohydride but the alkene functional group does not. [2] (v) Describe a chemical test that can be used to distinguish A and B. [2] …………………………………………………………………………………………………………….. …………………………………………………………………………………………………………….. …………………………………………………………………………………………………………….. …………………………………………………………………………………………………………….. …………………………………………………………………………………………………………….. ……………………………………………………………………………………………………………..

3 ©YIJC [Turn over …………………………………………………………………………………………………………….. …………………………………………………………………………………………………………….. …………………………………………………………………………………………………………….. …………………………………………………………………………………………………………….. …………………………………………………………………………………………………………….. …………………………………………………………………………………………………………….. …………………………………………………………………………………………………………….. …………………………………………………………………………………………………………….. …………………………………………………………………………………………………………….. …………………………………………………………………………………………………………….. …………………………………………………………………………………………………………….. …………………………………………………………………………………………………………….. …………………………………………………………………………………………………………….. …………………………………………………………………………………………………………….. …………………………………………………………………………………………………………….. ………………………………