PJC_H1 Chemistry_2008 JC2 H1 Chemistry Prelim Paper 2

1 Name: Index No: CT Group: 07 PIONEER JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATION 2008 CHEMISTRY 8872/02 Higher 1 Paper 2 16 September 2008 Additional Materials: Data Booklet 1 hour 30 minutes Writing papers READ THESE INSTRUCTIONS FIRST Write your name, CT Group and index number in the spaces at the top of this page. Write in dark blue or black pen. Answer all questions in Section A and any two questions in Section B. For Section A, write your answers in the spaces provided. For Section B, write your answers on the writing papers provided. If there is no answer to the question, a blank sheet of paper must still be submitted. You are advised to show all working in calculations. You may use a calculator. The number of marks is given in brackets [ ] at the end of each question or part question. At the end of the examination, fasten all your work securely together. FOR EXAMINER’S USE Section A Section B 1 / 4 1 / 20 2 / 5 2 / 20 3 / 4 3 / 20 4 / 9 5 / 8 6 / 10 TOTAL This document consists of 13 printed pages. [Turn Over

2 Section A (40 marks) Answer all questions in the spaces provided. 1 (a) Complete the table below. [2] Number of Particle Electric charge Mass number Protons Electrons Neutrons X 0 16 16 Y 1- 81 36 Z 70 31 28 (b) Sketch on the diagram below how a beam of particle Y and a beam of particle Z would be affected by the electric field. [2] [Total: 4] 2 CO3 2- and SO3 2- ions are commonly found in many compounds. Although they have the similar formulae, they have different shapes. (a) What is the main feature of the electron pair repulsion model for accounting for shapes of molecules or ions? [1] _ + Source beams of particle Y and particle Z

3 (b) By means of dot-and-cross diagrams, predict the shapes of the ions. Account for the difference. [4] [Total:5] 3 (a) Describe the combustion of magnesium and phosphorus in excess oxygen, writing an equation for each reaction. [3] (b) It is found that magnesium burns less readily than calcium. Suggest a reason why this i