NYGH 2013-S3EOY-Chem P2

Class Register Number Name 南洋女子中学校 NANYANG GIRLS’ HIGH SCHOOL End-of-Year Examination 2013 Secondary Three CHEMISTRY 1 hour 45 minutes Paper 2 Theory Paper 0915 - 1100 Wednesday 9th October 2013 Additional materials: Writing paper READ THESE INSTRUCTIONS FIRST Do not open this booklet until you are told to do so. Write your name, register number and class in the spaces at the top of this page and on any separate answer paper used. Section A (40 marks) Answer all questions. Write your answers in the spaces provided on the question paper. Section B (30 marks) Answer all questions including questions 8, 9 and 10 Either or 10 Or. Write your answers on the separate writing paper provided. At the end of the examination, 1. fasten all your work securely together; 2. tick 10 Either (for Either) or 10 Or (for Or) next to the number 10 in the grid below to indicate which question you have answered. INFORMATION FOR CANDIDATES Examiner’s Use Section A Section B 8 9 10 Either 10 Or Total The intended number of marks is given in the brackets [ ] at the end of each question or part question. You are advised to spend no longer than one hour on Section A and no longer than 45 minutes on Section B. Setters: CHG/LXT/MI This document consists of 13 printed pages. NANYANG GIRLS’ HIGH SCHOOL [Turn over

2013 End-of-Year Examination Secondary Three 2 Nanyang Girls’ High School Setters: LXT/CHG/MI Chemistry /II Section A Answer all questions. Write your answers in the spaces provided. A1 The names of some compounds are given below. carbon monoxide ammonium sulfate magnesium carbonate potassium hydroxide lead(II) iodide lead(II) nitrate aluminium oxide methane ethanoic acid Select from the above list, substance(s) that fit(s) the following descriptions. Each name may be used once, more than once or not at all. [4] (a) a salt which is prepared by precipitation _______________________ (b) two solutions, which, when added together and warmed, will produce a gas that turns moist red litmus paper blue _______________________ and _______________________ (c) a substance that dissolves in water, forming a solution which causes Universal Indicator to turn orange _______________________ Total [4] A2 Methylamine, CH 3NH2, is a derivative of ammonia, in which one H atom in ammonia is replaced by a CH3 group. (a) Draw a Lewis dot diagram to show the electronic arrangement of methylamine. [1]

2013 End- of-Year Examination Secondary Three 3 Nanyang Girls’ High School Setters: CHG/LXT/MI Chemistry /II [Turn over (b) As with ammonia, methylamine reacts with acids to form a salt only. In a reaction, it was found that 0.0250 mol of methylamine reacted completely with 20.0 cm3 of 0.0625 mol/dm3 of acid Q. Show, by calculations, the basicity of acid Q. [2] Total [3] A3 The arrangement of particles in solid Z, which is made of an unknown element Y and oxygen, is shown below. (a) In solid Z, what is the ratio of oxygen atoms to atoms of element Y? [1] _____________________________________________________________ atom of Y atom of oxygen

2013 End-of-Year Examination Secondary Three 4 Nanyang Girls’ High School Setters: LXT/CHG/MI Chemistry /II (b) Identify element Y, given that the percentage composition of oxygen atoms in solid Z is 23.9 %. Show your calculations in the space below to support your answer. [3] Element Y : _______________________ (c) Solid Z would react with both dilute sulfuric acid and aqueous sodium hydroxide. State the type of oxide Z is, and name another example of such an oxide. [2] _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ (d) Solid Z melts at 1975°C. (i) In terms of its structure and bonding, explain why solid Z has a high melting point. [2] ____________________________________________________ ____________________________________________________ ____________________________________________________ (ii) Explain another physical property solid Z is likely to have. [2] ____________________________________________________ ____________________________________________________ Total [10]

2013 End- of-Year Examination Secondary Three 5 Nanyang Girls’ High School Setters: CHG/LXT/MI Chemistry /II [Turn over A4 A gas sample of X was injected into the mass spectrometer and the result is shown below. Using the mass spectrum, calculat e the relative atomic mass of X and identify the element X. [2] Element F : _______________________ Total [2] 51.5 11.2 17.1 17.4 mass relative abundance (%) 100 50

2013 End-of-Year Examination Secondary Three 6 Nanyang Girls’ High School Setters: LXT/CHG/MI Chemistry /II A5 The following is an account of an experiment to determine the mass of copper(II) nitrate from a given quantity of nitric acid. A measuring cylinder was used to transfer 250 cm 3 of 2 mol/dm3 nitric acid to a beaker. 22.0 g of copper(II) oxide was weighed out. The acid was heated and the copper(II) oxide was added, a little at a time, with stirring, until the copper(II) oxide is present in excess. The mixture was filtered and the filtrate was heated until the volume has been reduced to about a third of its original. The solution was left to cool. The crystals that formed were filtered off and dried between pieces of filter paper. (a) What was observed to show that copper(II) oxide was in excess? [1] ________________________________________________________ (b) Explain which measurement was unnecessary. [2] ________________________________________________________ ________________________________________________________ (c) Why did crystals of copper(II) nitrate form when the filtrate was cooled? [1] ________________________________________________________ (d) Give an ionic equation, including state symbols, for the above reaction. [1] ________________________________________________________ (e) Calculate the maximum mass of copper(II) nitrate formed. [3] (f) Suggest one way to increase the yield of copper(II) nitrate crystals without changing the amount of the reactants used. [1] ________________________________________________________ Total [9]

2013 End- of-Year Examination Secondary Three 7 Nanyang Girls’ High School Setters: CHG/LXT/MI Chemistry /II [Turn over A6 Nitrogen dioxide is a dark brown gas. When 0.12 dm3 of nitrogen dioxide at room temperature and pressure is cooled, it forms a yellow liquid and then the pale yellow crystals. The crystals are heated and the temperature is measured every minute as shown in the graph below. (a) Calculate the number of molecules present in this sample of nitrogen dioxide. [2] (b) (i) Describe the arrangement and move ment of the molecules in the region AB. [2] __________________ __________________________________ __________________ __________________________________ __________________ __________________________________ (ii) Name the change that occurs in the region BC. [1] __________________ __________________________________