DHS Prelim P3_Qn

This question paper consists of 14 printed pages and 0 blank page. © DHS 2017 [Turn over Name: Index Number: Class: DUNMAN HIGH SCHOOL Preliminary Examination 2017 Year 6 H2 CHEMISTRY 9729/03 Paper 3 Section A and B (Free Response) 18 September 2017 2 hours Additional Materials: Data Booklet Writing Paper Cover Sheet INSTRUCTIONS TO CANDIDATES 1 Write your name, index number and class on this cover page and on the Cover Sheet provided. 2 Write your answers on the separate writing papers provided. 3 Write in dark blue or black pen. 4 You may use an HB pencil for any diagrams or graphs. 5 Start each question on a fresh sheet of paper. 6 At the end of the examination:  Fasten all your work securely together with the Cover Sheet on top. 7 Do not use staples, paper clips, glue or correction fluid. Section A 8 Answer all questions in this section. Section B 9 Answer one question from this section. The number of marks is given in brackets [ ] at the end of each question or part question. You are advised to show all workings in calculations. You are reminded of the need for good English and clear presentation in your answers.

2 © DHS 2017 9729/03 [Turn Over Section A Answer all questions. 1 (a) Singapore has been affected by severe smoke haze due to forest fires in the region periodically. The National Environment Agency (NEA) is taking action to ensure that its population is better equipped to deal with haze. During one of the sample analys is of air, the air sample was found to contain elevated amounts of NO2 and gas S. By careful measurement s and extrapolation, the value of 𝑝 ρ for gas S has been found to be approximately 110.3, at 100 °C and at very low pressure. [𝑝 is the pressure of the gas in Pa and ρ is the density of the gas in g m–3] 𝑝 (i) State two main assumptions of the kinetic theory, and use these to explain why you might expect the behaviour of nitrogen dioxide to be less ideal compared to that of hydrogen. [3] (ii) Calculate an approximate value for the relative molecular mass of S. [1] (iii) Hence, identify gas S, where S is a diatomic neutral pollutant. [1] (b) Atmospheric sulfur dioxide is a major air pollutant that forms acid rain. The pollution problem caused by sulfur dioxide is amplified in the presence of atmospheric oxides of nitrogen, which act as a homogeneous catalyst. Explain, with the aid of equation(s), how atmo