ACJC_H1_CHEM_P2_Qns

Index No. Name Form Class Tutorial Class Subject Tutor ANGLO-CHINESE JUNIOR COLLEGE DEPARTMENT OF CHEMISTRY Preliminary Examination CHEMISTRY 8872/02 Higher 1 Paper 2 16 August 2016 2 hours Candidates answer Section A on the Question Paper Additional Materials: Writing Paper Data Booklet READ THESE INSTRUCTIONS FIRST Write your name, index number, form class, tutorial class and subject tutor’s name on all the work you hand in. Write in dark blue or black pen. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, glue or correction fluid. The use of an approved scientific calculator is expected, where appropriate. Section A Answer all the questions. Section B Answer two questions on separate answer paper. 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 Question no. Marks Section A B4 B5 B6 TOTAL This document consists of 16 printed pages. 8872/02/Prelim/16 ANGLO-CHINESE JUNIOR COLLEGE © ACJC 2016 Department of Chemistry [Turn over

2 © ACJC 2016 8872/02/Prelim/2016 [Turn over Section A Answer all questions in this section in the spaces provided. 1 The element chromium was discovered in 1797 by French chemist Louis Nicolas Vauquelin. A number of naturally occurring isotopes of chromium have been identified as listed below. isotope relative isotopic mass natural abundance (%) 50Cr 49.95 4.34 52Cr 51.94 83.79 53Cr 52.94 9.50 54Cr 53.94 2.37 (a) Use the above data to calculate the relative atomic mass of chromium to two decimal places. [2] Chromium is a transition metal. (b) (i) Describe the bonding in the element chromium. Draw a diagram to illustrate your answer. ………………………………………………………………………………………….. ……………………………………………………………………………………… [1]

3 © ACJC 2016 8872/02/Prelim/2016 [Turn over (ii) State two physical properties that you would expect chromium metal to possess. Explain, in terms of the bonding present, why it possesses these properties. property ………………………………………………….……… explanation .…………………… …………………………………………………..... …………………………………………………………………………….................. …………………………………………………………………………………...…..... property ………………………………………………….……… explanation .…………………… …………………………………………………..... …………………………………………………………………………….................. …………………………………………………………………………………...…...[3] (iii) Chromium metal is produ