NJC 2018_SH1 H1 Promo Paper 2 Answer

1 NJC Promotional Examination 887302/18 [Turn over SUBJECT CLASS REGISTRATION NUMBER CHEMISTRY Paper 2 Structured Questions Additional Materials: Data Booklet Writing Papers 8873/02 Mon 1 October 2018 1.5 hours READ THE INSTRUCTIONS FIRST Write your subject class, registration number and name on all the work you hand in. Write in dark blue or black pen on both sides of the paper. You may use a soft pencil for any diagrams, graphs or rough working. Do not use paper clips, highlighters, glue or correction fluid. Answer all questions in Section A (40 marks) in the space provided on the Question paper. Answer one question in Section B (20 marks) on the writing paper provided separately. The use of an approved 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. Appropriate significant figures and units are expected for final numerical answers For Examiner’s Use 1 / 8 2 / 7 3 / 7 4 / 9 5 / 9 6 /20 Paper 2 / 60 Paper 1 / 20 Overall Total / 80 Overall percentage / 100 NATIONAL JUNIOR COLLEGE SH1 PROMOTIONAL EXAMINATION Higher 1 CANDIDATE NAME

2 NJC Promotional Examination 8873/02/18 Answer ALL questions in the spaces provided. 1 (a) The element nickel was discovered in 1751 by Swedish chemist A. F. Cronstedt. (i) Nickel is a transition metal. Describe the bonding in the element nickel. You should draw a labelled diagram to illustrate your answer. Metallic bonding is present in nickel, which is the electrostatic attraction between (positive) nickel ions and its delocalised (or a sea of) electrons. [1] [1] [2] (ii) State two physical properties that you would expect nickel metal to possess. Explain, in terms of the bonding present, why it possesses these properties. property Good electrical conductivity [1/2] explanation delocalised sea of electrons are mobile electrons that can act as charge carriers. [1] property high melting/boiling point [1/2] explanation strong electrostatic force of attraction between positive metal ions and sea of delocalised electrons requiring a large amount of energy to break. [1] [3] (b) A common battery is the nickel -cadmium cell. It has one electrode of cadmium and one electrode of nickel ( III) hydroxide, Ni(OH) 3. The two electrodes are connected using an electrolyte. The two half-equations for this cell are: Cd(OH)2 + 2e− Cd + 2OH− Ni(OH)3