IJC_2008_H1 Chemistry_Prelim II_Paper2

INNOVA JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATIONS 2 in preparation for General Certificate of Education Advanced Level Higher 1 CANDIDATE NAME CLASS INDEX NUMBER CHEMISTRY Paper 2 Structured and Free Response Questions Section A: Structured Candidates answer Section A on the Question Paper Section B: Free Response Additional Materials: Writing Papers Graph Paper Data Booklet 8872/02 15 September 2008 2 hour READ THESE INSTRUCTIONS FIRST Write your index number, name and civics group on all the work you hand in. Write in dark blue or black pen. You may use pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. For Examiner’s Use Section A 1 10 2 12 3 10 4 8 Significant Figures Handwriting Total 40 Section A: Structured Questions (40m) Answer all questions in the space provided. Section B: Free Response Questions (40m) Answer two questions on separate writing papers. You are advised to show all working in calculations. You are reminded of the need for good English and clear presentation in your answers. You are reminded of the need for good handwriting. Your final answers should be in 3 significant figures. 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. This document consists of 15 printed pages and 1 blank page. [Turn overInnova Junior College

2 © INNOVA 2008 8872/02 [Turn over For Examiner’s Use Section A Answer ALL questions on the space provided 1. Hydrazine is a chemical compound with the formula N 2H4. It has an ammonia-like odour, and is derived from the same industrial chemistry processes that manufacture ammonia. However, hydrazine has physical properties that are more similar to those of water. Hydrazine is used as rocket fuel as it decomposes into ammonia and nitrogen gas. This reaction is extremely exothermic and thus very suitable as an efficient thruster propellant. (a) Draw the Lewis structure for the hydrazine molecule. State its shape and indicate the H–N–H bond angle. Shape: ………………………. [2] (b) Write a balanced equation to illustrate the decomposition of hydrazine. ……………………………………………………………………………....….....….... [1] (c) Suggest a reason why the decomposition reaction is highly exothermic. ……………………………………………………………………………....…..…....… [1] (d) Hydrazine is al