MI Prelim 9647 P1 Answers

Class Adm No Candidate Name: This question paper consists of 16 printed pages and 2 blank pages. 2017 Preliminary Examinations II Pre-University 3 H2 CHEMISTRY 9647/01 Paper 1 Multiple Choice 20 Sept 2017 1 hour Additional materials: Multiple Choice Answer Sheet Data Booklet READ THESE INSTRUCTIONS FIRST Do not turn over this question paper until you are told to do so Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. Write your name, class and admission number in the spaces provided at the top of this page and on the Multiple Choice Answer Sheet provided. There are forty questions on this paper. Answer ALL questions. For each question there are four possible answers A, B, C and D. Choose the one you consider correct and record your choice in soft pencil on the Multiple Choice Answer Sheet provided. Read the instructions on the Multiple Choice Answer Sheet very carefully. Each correct answer will score one mark. A mark will not be deducted for a wrong answer. Any rough working should be done in this question paper. The use of an approved scientific calculator is expected, where appropriate. FOR EXAMINER’S USE TOTAL (40 marks)

2 Section A For each question there are four possible answers, A, B, C, and D. Choose the one you consider to be correct. 1 Dolomite is a carbonate-containing mineral with formula MgZ(CO3)2 where Z is a metal ion. It is insoluble in water but reacts with acids. When 2.00 g of dolomite was completely dissolved in an excess of hydrochloric acid, 0.759 g of carbon dioxide was given off. What is the identity of the metal Z? A Ba B Ca C Ra D Sr 2 Sulfur dioxide gas is an irritant to the eyes and respiratory system. The maximum safe toleration level of sulfur dioxide in air is 0.014 mg dm-3. How many molecules of sulfur dioxide gas are present in 1 dm3 of air at this toleration level? A 0.014 6.02 × 1023 × 64.1 B 0.014 1000 × 1 64.1 × 6.02 × 1023 C 0.014 64.1 × 6.02 × 1023 D 0.014 1000 × 64.1 × 6.02 × 1023 3 The element technetium, Tc (mass number 99; atomic number 43), was discovered in 1937 by two Italian scientists, Segŕe and Perrier. Under suitable conditions, technetium reacts with fluorine to form TcF6. Which of the following options shows the correct number of protons, neutrons and electrons in Tc6+? number of protons number of neutrons number of electrons A 43 43 56 B 43 56 37 C 49 43 37 D 43 56 49

3 [Turn over 4 Which of the following atoms has three unpaired electrons? A Br B Co C Ga D Sc 5 Under standard conditions, water exists in the liquid state but hydrogen sulfide exists in the gaseous state. Which of the following best explains this phenomenon? A Water has a higher relative molecular mass than hydrogen sulfide. B The O -H covalent bond in water is stronger than the S -H covalent bond in hydrogen sulfide. C The hydrogen bonds between water molecules are stronger than the Van der Waals’ forces between hydrogen sulfide molecules. D Hydrogen sulfide has a more spherical structure compared to water. 6 Antimony, Sb, is in Group V of the Periodic Table. It was proposed that antimony is able to form SbF4n- anion, the structure of which is of square planar shape. Which of the following shows the correct value of n and the oxidation number of Sb in this anion? value of n oxidation number of Sb A 1 +3 B 1 +5 C 3 +1 D 3 +3

4 7 X and Y are ideal gases that do not react with one another. The molar mass of X is twice that of Y. If all measurements are taken at room temperature and pressure, which statement correctly describes X and Y? A The volume occupied by 2 g of X is half that occupied by 2 g of Y. B The mass of 5 dm3 of X is half that of 5 dm3 of Y. C The volume occupied by 2.5 g of X is equal to the volume occupied by 5 g of Y. D On mixing 1 dm3 of X with 1 dm3 of Y, the partial pressure of X is twice that of Y. 8 The two steps in the conversion of compound P to compound R are shown below. P  Q Step 1 Q  R Step 2 The energy profile of the reaction is shown below. Which of the following statements about the reaction can be deduced from the information given? A The enthalpy change for the reaction is endothermic. B Q acts as a catalyst in the reaction. C Step 1 is the rate determining step. D R is thermodynamically less stable than P. P energy progress of reaction Q R

5 [Turn over 9 When liquid SOCl2 is added to Ba(OH) 2, a vigorous reaction occurs and the temperature decreases from 25 °C to 5 °C. What are the correct signs of H, S and G for this reaction? H S G A + + - B + - + C - + - D - - + 10 A sample of finely ground copper was contaminated with zinc powder. Treatment of the sample with an excess of hydrochloric acid produced 120 cm 3 of hydrogen gas, measured at room temperature and pressure. The remaining copper was then reacted with acidified potassium manganate(VII). It was found that 0.00424 mol of potassium manganate( VII) was required for complete oxidation of copper to copper(II) ions. What is the percentage by mass of copper in the sample? A 45.2% B 65.8% C 67.3% D 90.4% 11 Zinc(II) reacts with the complex anion hexacyanoferrate( III), [Fe(CN) 6]3-, to give a sparingly soluble salt which dissociates in water according to the following equilibrium. Zn3[Fe(CN)6]2(s) ⇌ 3Zn2+(aq) + 2[Fe(CN)6]3-(aq) If the solubility product, K sp, of Zn3[Fe(CN)6]2 is X, what is the concentration of Zn 2+(aq) at equilibrium? A (3X 2 ) 1 3 B (3X 2 ) 1 5 C (9X 4 ) 1 3 D (9X 4 ) 1 5

6 12 Which of the following statements about the rate constant, k, of chemical reactions is not true? A The rate constant increases when temperature increases. B The rate constant increases when the concentration of the reactant increases. C The rate constant decreases when the activation energy increases. D The units of the rate constant depends on the overall order of reaction. 13 A Period 3 element forms an oxide that is soluble in both water and aqueous sodium hydroxide. Which of the following could be the identity of this element? A aluminium B silicon C sodium D sulfur 14 In which of the following pairs is the radius of the first species greater than that of the second species? A Mg, Al B Ca, Ba C Mg2+, Na+ D K+, Ar 15 Which of the following properties of the Group II elements and their compounds decreases down the group? A Ease of oxidation of the elements B Electronegativity of the elements C Reactivity of elements with chlorine D Thermal stability of nitrates 16 With reference to the chemistry of Group VII elements and their compounds , which of the following would be a correct prediction for astatine? A Astatine reacts vigorously with hydrogen at room temperature. B Astatine exists as a gas at room temperature. C Astatine reacts with cold aqueous hydroxide to form AtO - and At -. D Molten AlAt3 can conduct electricity.

7 [Turn over 17 Which of the following products is least likely to act as a ligand? A AlH3 B CO C C2H5OH D CH3NH2 18 The use of Data Booklet is relevant to this question. An element G has an atomic number of 23. Which of the following compounds of G is not likely to exist? A KGO3 B G2O5 C K2GO4 D GOCl2 19 Which of the following species could be an intermediate in an electrophilic addition reaction? A B C D 20 How many structural isomers with the molecular formula C 5H10O gives an orange precipitate with Brady’s reagent and a yellow precipitate with alkaline aqueous iodine? A 1 B 2 C 3 D 4

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