MI 2008 PU2 Promotional H1Chem P1 ans

Class Adm No Candidate Name: _______________________ Promotional Examinations 2008 Pre-university 2 CHEMISTRY HIGHER 1 8872/1 Monday 8 th Sept 2008 50 minutes Additional materials: Answer paper Data Booklet 1 piece of foolscap paper READ THESE INSTRUCTIONS FIRST Do not open this booklet until you are told to do so. Write your name, index number and cla ss on the answer sheet in the spaces provided and at the top of this page. There are thirty questions in 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 separate answer sheet. Read the instructions on the 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 booklet. This question paper consists of 12 printed pages.

Section A: Multiple Choice Questions (30m) For each question, there are 4 possible answers, A, B, C and D. Choose the one that you consider correct. 1. Which of the following contains 9.03 × 10 21 of atoms? A 2.25 g of methane B 0.6375 g of ammonia C 336 cm 3 of argon gas at standard temperature and pressure D 3.60 dm 3 of fluorine gas at room temperature and pressure 2. On heating chromite, FeCr 2O4 with sodium carbonate in air, the following reaction occurs: 4FeCr2O4 + 8Na2CO3 + 7O2Æ 8Na2CrO4 + 2Fe2O3 + 8CO2 Which species is oxidised and which species is reduced in this process? Species oxidised Species reduced A Chromium only Carbonate ion only B Chromium only Carbonate ion and oxygen C Chromium and iron Oxygen only D Chromium and iron Carbonate ion and oxygen 3. The successive ionization energies, in kJ mol -1, of an unknown element E are given below. 420 3100 4400 5900 8000 9600 11400 13300 Which of the following statements about E is correct? A E is in group II of the Periodic Table. B The oxide of E is an amphoteric oxide. C The chloride of E hydrolyses in water to give an acidic pH. D Element E can conduct electricity in the solid and molten state. [Turn over 2

4. Which electronic configuration is t hat of an atom of an element which is isoelectronic with H2S? A 1s 2 2s2 2p6 3s2 B 1s 2 2s2 2p6 3s2 3p2 C 1s 2 2s2 2p6 3s2 3p4 D 1s 2 2s2 2p6 3s2 3p6 5. Which of the following pairs contai ns a compound held by ionic attractions and a compound held by permanent dipole-permanent dipole attractions? A sodium chloride, tetrachloromethane B strontium, bromoethane C aluminium fluoride, phosphorus trichloride D sodium ethanoate, beryllium hydride 6. How many σ and π bonds are there in linear C2H2 molecule? A 2 σ and 2π B 2 σ and 3π C 3 σ and 1π D 3 σ and 2π 7. Why is the boiling point of butanone (79.6 oC) higher than that of pentane (36.1oC)? A The relative molecular mass of bu tanone is higher than that of pentane molecule B The butanone molecule has a lar ger surface area than that of a pentane molecule C There are permanent dipole-permanent dipole forces between butanone molecules, but only van der Waals’ forces between pentane molecules. D There are hydrogen bonds betw een butanone molecules, but not between pentane molecules. [Turn over 3

8. Given that the enthalpy change of neutralisation for the reaction given below is -114kJmol-1, 2NaOH(aq) + H2SO4(aq) Æ Na2SO4(aq) + 2H2O(l) What is the most likely value for t he enthalpy change of neutralization for the following reaction? 2Ba(OH)2(aq) + 2HCl(aq) Æ BaCl2(aq) + 2H2O(l) A -57 kJmol -1 B -76 kJmol -1 C -114 kJmol -1 D -228 kJmol -1 9. The radii of the ions P 3-, S2- and Cl - are 0.212nm, 0. 184nm and 0.181nm respectively. Which of the following correctly explains why the radius decreases from P3- to Cl-? A An increase in the total number of electrons and in the nuclear charge B An increase in the total number of electrons and the nuclear charge remaining constant. C A constant total number of elec trons and an increase in the nuclear charge D A decrease in the total number of electrons with nuclear charge remaining constant. 10. Which of the following changes does not take place in a period of elements with increasing atomic number? A The atomic radius of the elements decreases. B The oxides of the elements become less acidic. C The electrical conductivity generally decreases. D The electronegativity of the elements increases. [Turn over 4

11. Which oxide will not dissolve in aqueous sodium hydroxide? A Al 2O3 B MgO C SO 2 D SiO 2 12. The following reaction is endothermic. k 1 Reactants Products ΔH > 0 k –1 Which of the following represents the changes when the equilibrium mixture is cooled? k 1 k –1 K c A increases increases increases B decreases decreases decreases C increases decreases increases D decreases increases decreases 13. If the reaction P + Q Æ R + S is described as being zero order with respect to P, which of the following statements best describes P? A P is a catalyst in the above reaction. B The concentration of P does not change during the reaction. C There are no P molecules which possess sufficient energy to react. D The rate of reaction is i ndependent of the concentration of P. [Turn over 5

14. The reaction of a compound RS is shown below. RS (g) → R (g) + S (g) The rate equation for the reaction is rate = k [RS] and the half-life of the reactant is found to be 192.5 s. If the initial concentration of RS is 2.0 x 10 -2 mol dm -3 , what will be the concentration of RS after 385 seconds? A 1.0 x 10 -2 mol dm -3 B 5.0 x 10 -3 mol dm -3 C 2.5 x 10 -3 mol dm -3 D 2.0 x 10 -3 mol dm -3 15. 1 mole of solid I2 was added to 50 cm3 of 3 mol dm–3 KI. Equilibrium was reached. The reaction mixture was then rapidly cooled and aqueous AgNO3 was added until no further precipitation occurred. The mass of precipitate was 11.75 g. Calculate the value of Kc for the reaction. I 2(s) + I–(aq) I3 –(aq) A 2.22 B 2.00 C 0.15 D 0.11 [Turn over 6

16. Aqueous sodium chlorate(I), NaOCl, is used to keep swimming pool water free of harmful bacteria. It is the HOCl molecules formed when NaOCl reacts with water to that kill bacteria. OCl-(aq) + H2O OH-(aq) + HOCl(aq) The OCl- ion is broken down by ultra-violet light from the sun. OCl -(aq) + uv light Æ Cl-(aq) + ½ O2(g) What could be done to maintain the highest concentration of HOCl(aq)? A Acidify the pool water B Add a solution of chloride ions C Add a solution of hydroxide ions D Bubble air through the water 17. Consider the equilibrium system Fe 3O4(s) + CO(g) CO2(g) + 3 FeO(s) It is an endothermic reaction at room temperature. Which of the following changes is incorrect ? A Reducing CO 2 causes the position of equilibrium to shift to the right. B Reducing CO causes the position of equilibrium to shift to the left. C Adding Fe 3O4 causes the position of equilibrium to shift to the right. D Decreasing the temperature causes the position of equilibrium to shift to the left. 18. Acidosis is a condition caused by strenuous exercise in which the pH of human blood falls from the normal value of 7.4 and death may occur should pH drops to 6.8 By how many times is the H + ion concentration in blood at pH 6.8 greater than that at pH 7.4? A 1.1 B 2.0 C 4.0 D 60.0 [Turn over 7

19. In which of the following equations does the H2O ion act as a bronsted base? A CH 3COOH(aq) + H2O(l) CH3COO- (aq) + H3O+ (aq) B CO 3 2- (aq) + H2O(l) HCO3 - (aq) + OH- (aq) C HS - (aq) + H2O(l) H2S(aq) + OH- (aq) D HSO 3 - (aq) + H2O(l) H2SO3(aq)