University of KwaZulu-Natal, Westville Campus, Durban Examinations: May 2010 GENERAL PRINCIPLES OF CHEMISTRY - CHEM110

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1 GENERAL PRINCIPLES OF CHEMISTRY - CHEM110 Section A Multiple Choice Questions Total Marks for Section A: 23 Duration: 3 hours Total Marks for Examination: 100 Internal Examiners: G.D. Dawson, H. Govender, B.S. Martincigh, B. Moodley, L. Pillay Moderating Board: M. Bala, C. Southway, W. van Zyl INSTRUCTIONS: 1. Answer ALL questions. 2. There is only one correct answer for each question. 3. There is no negative marking. 4. Your answers must be written on the answer sheet provided. 5. You must mark a cross (X) on only one correct answer. 6. This question paper consists of 8 pages. Please check that you have them all. 7. You are required to hand in this question paper at the end of the examination. 8. You will also require a copy of Section B of the examination paper. 9. You are advised not to spend more than 45 minutes on Section A. 10. A periodic table and data sheet is provided.

2 For each of the following questions, select the correct answer from the list provided. There is only one correct answer for each question. Indicate your answer on the answer sheet provided. 1. The molar mass of manganese(ii) sulfate is A) g mol -1 B) g mol -1 C) g mol -1 D) g mol The correct name for BeSO 4 4H 2 O is A) beryllium sulfide tetrahydrate B) beryllium sulfate tetrahydrate C) beryllium sulfate hydroxide D) beryllium sulfide hydroxide 3. How many moles of K 3 PO 4 are required to produce 9 moles of KCl in the following reaction: 3CaCl 2 (aq) + 2K 3 PO 4 (aq) Ca 3 (PO 4 ) 2 (s) + 6KCl(aq)? A) 1.5 B) 4.5 C) 2 D) 3 2

3 4. Carry out the following mathematical operations and report the answer with the correct number of significant figures ( ) A) 6.69 B) 6.7 C) 7 D) The oxidation state of Cl in HClO 2 is A) +3 B) -1 C) +1 D) Pb has A) 82 protons, 82 electrons, 125 neutrons B) 82 protons, 82 electrons, 207 neutrons C) 207 protons, 207 electrons, 82 neutrons D) 207 protons, 82 electrons, 125 neutrons 7. Choose the correct answer from the following: A) 730 mmhg = Pa B) 18 Torr = N m -2 C) 433 Torr = 433 mmhg D) 760 mmhg = 10 atm 3

4 8. Avogadro s law states that, at a fixed pressure and temperature, the volume of a gas is directly proportional to A) the temperature in Kelvin. B) the number of moles present. C) the ideal gas constant. D) None of these. 9. High energy photons correspond to light which has a: A) low frequency B) long wavelength C) short wavelength D) high frequency and long wavelength 10. The ground state electron configuration for chloride, Cl, is: A) 1s 2 2s 2 2p 6 3s 2 3p 5 B) [Ne]3s 2 3p 4 C) [Ne]3s 2 3p 6 4s 1 D) 1s 2 2s 2 2p 6 3s 2 3p A possible set of quantum numbers corresponding to the highest energy electron in the ground state of cesium, Cs, is: A) n = 6, l = 0, m l = 0, m s = +½ B) n = 6, l = 2, m l = 2, m s = -½ C) n = 6, l = 1, m l = -1, m s = -½ D) n = 6, l = 0, m l = 1, m s = +½ 4

5 12. In the molecule below, which atom has the largest partial negative charge? F Br C Cl I A) Cl B) F C) I D) Br 13. In which of the molecules below, is the carbon-carbon distance the shortest? A) H 2 C=CH 2 B) H-C C-H C) H 3 C-CH 3 D) H 2 C=C=CH Which of the following molecules does not obey the octet rule? A) NH 3 B) SeF 2 C) BF 3 D) AsF 3 5

6 15. According to VSEPR theory, if there are three electron pairs on a central atom, they will be arranged such that the angles between the electron pairs are: A) 90 B) 180 C) D) Which one of the following derivatives of ethane has the highest boiling point? A) C 2 Br 6 B) C 2 F 6 C) C 2 I 6 D) C 2 Cl For the reaction: 2N 2 O 5 (g) 4NO 2 (g) + O 2 (g), at the time when N 2 O 5 is being consumed at a rate of mol dm -3 s -1, what is the rate at which O 2 is being formed? A) mol dm -3 s -1 B) mol dm -3 s -1 C) mol dm -3 s -1 D) mol dm -3 s -1 6

7 18. The Arrhenius equation, k = Ae-E a /RT, expresses the relationship between the reaction rate constant, k, and the energy of activation, E a. The probability that colliding molecules will react A) increases with increasing energy of activation. B) depends only on the empirical constant, A. C) increases with decreasing temperature. D) decreases with increasing energy of activation. 19. A catalyst facilitates a reaction by A) making the reaction more exothermic. B) shifting the position of the equilibrium of the reaction. C) increasing the activation energy for the reverse reaction. D) lowering the activation energy of the reaction. 20. For the following reaction: CaO(s) + CO 2 (g) CaCO 3 (s), the equilibrium constant expression is A) K c = [CaCO 3 ]/[CaO] B) K c = [CO 2 ] C) K c = [CaCO 3 ]/[CaO][CO 2 ] D) K c = 1/[CO 2 ] 21. For a specific reaction, which of the following statements can be made about the equilibrium constant? A) It always remains the same. B) It increases if the concentration of one of the products is increased. C) It changes with a change in temperature. D) It may be changed by the addition of a catalyst. 7

8 22. The conjugate base of H 2 S is A) S 2 B) H 2 O C) H + D) HS 23. In an aqueous solution of ph 9: A) The hydroxide ion concentration is zero. B) The hydrogen and hydroxide ion concentrations are the same. C) The hydroxide ion concentration exceeds the hydrogen ion concentration. D) The hydrogen ion concentration exceeds the hydroxide ion concentration. End of Section A [23] 8

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