NYGH 2012-S3BT2-Chem

Class Register Number Name 南洋女子中学校 NANYANG GIRLS' HIGH SCHOOL BLOCK TEST 2 Secondary Three CHEMISTRY 1 hour Thursday 5th July 2012 1030 - 1130 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. Please note that if you do not write your answers in the spaces provided specially for that purpose, that section of the paper will be awarded ZERO marks. Choice) Section A (15 MCQ) This section consists of 15 multiple choice questions. Choose the best answer and write its letter in the space provided on page 2 of the Question Paper. Section B (Structured) Answer all questions in the spaces provided on the Question Paper. Section C (Free-Response) Answer all questions in the spaces provided on the Question Paper. Submit Sections A, B and C together. INFORMATION FOR CANDIDATES The intended number of marks is given in the brackets [ ] at the end of each question or part question. A copy of the Periodic Table is printed on page 12. Topics to be tested: Particulate nature of matter/ Kinetic particle theory Atomic structure and separation technique Chemical bonding Mole concept Examiner’s Use Section A (15 marks) Section B (20 marks) Section C (10 marks) Total (45 marks) Setter: C.W. This document consists of 12 printed pages. NANYANG GIRLS' HIGH SCHOOL [ Turn over]

2012 Block Test 2 Nanyang Girls’ High School Secondary Three Setter: C.W. Chemistry 2 Section A (15 Marks) Answer the questions (1-15) by filling the answer in the table below. 1 6 11 2 7 12 3 8 13 4 9 14 5 10 15 Section B (20 marks) Answer all questions in this section in the spaces provided. B1 (a) State the structure of diamond and tin(IV) iodide in the table above. [2] Substance Structure of substance Diamond Carbon dioxide Simple molecular structure Tin(IV) iodide (SnI4) Copper Metal lattice (b) Explain why carbon dioxide has a low melting point while diamond has a high melting point. [3]

2012 Block Test 2 Nanyang Girls’ High School Secondary Three Setter: C.W. Chemistry [Turn Over] 3 (c) Explain why copper conducts electricity in the solid state. [1] (d) Draw the “dot-and-cross” diagram to show the bonding in tin(IV) iodide. Show only the valence electrons. [1] (e) Draw the “dot-and-cross” diagram to show the bonding in carbon dioxide. Show only the valence electrons. [1] B2 Dichloromethane (CH2Cl2) was detected on a fibre found in a crime scene. A mass spectrometer was used to analyze the dichloromethane and it showed that the two chlorine isotopes, chlorine-35 and chlorine-37, were present. The mass spectrum also showed three peaks corresponding to different relative molecular masses of dichloromethane and the intensities of the peaks from the smallest relative molecular mass to highest relative molecular mass are in the ratio of 9:6:1. (The intensities of the peak show the relative abundance.) Relative abundance Relative molecular mass

2012 Block Test 2 Nanyang Girls’ High School Secondary Three Setter: C.W. Chemistry 4 (a) State the three relative molecular mass of dichloromethane in the mass spectrum. [1] (b) A piece of clothing contaminated with dichloromethane was obtained from a suspect and analyzed using the mass spectrometer. The average relative molecular m ass of dichloromethane found on the piece of clothing is 85. Explain clearly, showing relevant working, if the suspect is the criminal. [3] (c) Draw the “dot -and-cross” diagram to show the bonding in dichloromethane. Show only the valence electrons. [1] B3 A student wants to investigate the diffusion rates of two gases, ammonia and sulfur dioxide. Suggest a method whereby she is able to scientifically determine which gas has a higher diffusion rate. [3]

2012 Block Test 2 Nanyang Girls’ High School Secondary Three Setter: C.W. Chemistry [Turn Over] 5 B4 The empirical formula of a gas is PQ3. The relative atomic masses of P and Q are 12 and 1 respectively. (a) If the relative molecular mass of the gas is 30, determine the molecular formula of the gas. [1] (b) A sealed cylinder contains 48 dm3 of the gas in B4(a) at room temperature and pressure. What is the mass of the gas in the cylinder? [2] (c) What is the number of gas particles present in the cylinder? [1]

2012 Block Test 2 Nanyang Girls’ High School Secondary Three Setter: C.W. Chemistry 6 Section C (10 marks) Answer all questions in this section in the spaces provided. C1 Antimony, Sb, forms an oxide with the formula, SbxOy. Numerical answers are to be given to three significant figures. (a) (i) Calculate the number of moles present in 40.0 g of antimony. [1] (ii) Calculate the number of moles present in 7.90 g of oxygen gas. [1] (iii) Write the chemical equation with state symbols when 40.0 g of antimony reacts completely with 7.90 g of oxygen gas to form antimony oxide. [4]

2012 Block Test 2 Nanyang Girls’ High School Secondary Three Setter: C.W. Chemistry [Turn Over] 7 (b) What is the mass of 0.200 mol of antimony oxide as determined from C1(a)(iii)? [2] (c) A student referred to a data booklet and concluded that the formula of antimony oxide is Sb2xO2y and not SbxOy. Explain whether you agree with the student’s conclusion. [2] END OF TEST

2012 Block Test 2 Nanyang Girls’ High School Secondary Three Setter: C.W. Chemistry 8 Section A (15 marks) Choose the most suitable answer and write its letter in the answer table provided on Page 2. 1 Which method can be used to test the purity of a dye before it is use d in food flavouring? A Solubility in ethanol B Boiling point C Electrical conductivity D Ductility Please refer to the diagram below to answer Question 2 and 3. The initial water level is at R. 2 Choose the correct combination of gases that will cause the water level on the right to increase initially to Q. Gas X Gas Y A Sulfur dioxide Argon B Methane Oxygen C Argon Water vapour D Oxygen Ammonia 3 Which position will the water level be at after a day if gas X is carbon dioxide and gas Y is ammonia? A P B Q C R D S

2012 Block Test 2 Nanyang Girls’ High School Secondary Three Setter: C.W. Chemistry [Turn Over] 9 4 Which covalent substance conducts electricity? A Graphite B Diamond C Brass D Fluorine 5 Element X has atomic number 6 and element Y has atomic number 17. Which of the following statements is correct? A The two elements will form an ionic compound with the formula, XY2. B The two elements will form an ionic compound with the formula, XY4. C The two elements will form a covalent compound with the formula, XY2. D The two elements will form a covalent compound with the formula, XY4. 6 Which of the following substance s will be a good conductor of electrici