2023 TJC H2 Chem Prelim P2 (Ans)

9729 / TJC PRELIM / 2023 DO NOT WRITE IN THIS MARGIN [Turn over TEMASEK JUNIOR COLLEGE 2022 JC2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME ANSWERS CENTRE NUMBER S INDEX NUMBER Chemistry 9729/02 Paper 2 Structured Questions 23 August 2023 2 hours Candidates answer on the Question Paper. Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Write your Centre number, index number, name and CG in the spaces at the top of this page. 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 the questions in the spaces provided on the Question Paper. 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 17 printed pages and 3 blank page. For Examiner’s Use Paper 1 /30 Paper 2 Q1 Q2 Q3 Q4 Q5 Q6 Total /75 Paper 3 /80 TOTAL (%) /100

2 DO NOT WRITE IN THIS MARGIN 9729 / TJC PRELIM / 2023 DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN Answer all the questions in the space provided. 1 Atoms and ions of elements are made up of the three subatomic particles, protons, electrons and neutrons, in varying amounts. (a) Complete the following table to show the number of each particle in 7Li+ and 14C2–. Ion protons electrons neutrons [1] 14C2– 6 8 8 [1] 7Li+ 3 2 4 [2] (b) Separate beams of 14C2– and 7Li+ ions are passed through an electric field in the set- up below. The angle of deflection of the 14C2– beam is 7.0o. Sketch on the diagram below, the paths taken by beams of 7Li+ and 14C2– ions in the presence of an electric field. Label your sketch clearly. [2] [Total: 4] 14C2– 7Li+ 7o 7o [1] direction [1] equal angle

3 DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN 9729 / TJC PRELIM / 2023 DO NOT WRITE IN THIS MARGIN [Turn over 2 (a) (i) Explain what is meant by the term ‘electronegativity’, and how it relates to the concept of bond polarity. [2] [1] Electronegativity refers to the ability of an atom to attract the shared electron pair in a covalent molecule/bond [1] Bond polarity is a measure of how equally the electrons are shared between the two bonded atoms. Bonded atoms with different electronegativities will result in a polar bond. (ii) State and explain the change in electronegativity across a period in the Periodic Table. [2] Across a Period ✓ Nuclear charge increases as number of prot