CHEM1109 Example Multiple Choice Questions

Transcription

1 HM09 xample Multiple hoice Questions The following multiple choice questions are provided to illustrate the type of questions used in this section of the paper and to provide you with extra practice. It is not a sample quiz. The questions in the paper will be in the style of these questions but may well cover different topics. In the exam, the answer should be indicated by clearly circling the letter next to the choice you make and by filling in the corresponding box on the computer-marked sheet provided. The marks for each correct answer are given beside each question. Instructions for use of the computer sheet. raw a thick line through the centre and crossing both edges of each box selected, as in this example. Use a dark lead pencil so that you can use an eraser if you make an error. rrors made in ink cannot be corrected you will need to ask the examination supervisor for another sheet. oxes with faint or incomplete lines or not completed in the prescribed manner may not be read. e sure to complete the SI and name sections of the sheet. Your answer as recorded on the sheet will be used in the event of any ambiguity. There is only one correct choice for each question. egative marks will not be awarded for any question.

2 HM09 ovember 2008 xample Multiple hoice Questions. Which statement correctly describes Hess's Law? The enthalpy of all reactants in their standard states is defined as zero. nthalpy changes may only be calculated if one or more of the reactants is an element. The enthalpy change of a reaction is independent of the route taken. The enthalpy change of a reaction may only be calculated at atm pressure and 25. xothermic reactions occur quickly, endothermic reactions occur slowly. 2. Which one of the following statements best describes the standard enthalpy of formation of any element? The value of ΔH f (element) depends on temperature. The value of ΔH f (element) is zero only for elements in the solid state. The value of ΔH f (element) is zero for any element in the standard state. The value of ΔH f (element) is zero only at absolute zero temperature. The value of ΔH f (element) depends on S for that element. 3. Under which circumstances would a reaction be non-spontaneous at all temperatures? ΔH negative and ΔS positive ΔH negative and ΔS negative ΔH positive and ΔS negative ΔH positive and ΔS positive It is impossible to tell without calculating ΔG. 4. In which direction will the following equilibrium shift if a solution of H 3 O 2 a is added? H 3 OOH(aq) H 3 O 2 (aq) + H + (aq) shift to the right (more products) shift to the left (more reactant) no change cannot be predicted 5. In which of the following acid / base titrations, can we OT determine the equivalence point in an accurate manner? strong acid / strong base strong acid / weak base weak acid / strong base weak acid / weak base

3 HM09 ovember 2008 xample Multiple hoice Questions 6. What is the expression for K a for the following reaction? H 3 OOH(aq) H 3 O 2 (aq) + H + (aq) K a = [H 3 O 2 (aq)][h + (aq)]/[h 3 OOH(aq)] K a = 2[H + (aq)]/[h 3 OOH(aq)] K a = [H + (aq)] 2 /[H 3 OOH(aq)] K a = [H 3 OOH(aq)]/[H + (aq)] 2 7. Rank the following M water solutions in order of decreasing freezing point. al glucose al 2 H 3 OOH a 3 PO 4 highest freezing point lowest freezing point al > glucose > al 2 > H 3 OOH > a 3 PO 4 glucose > al > al 2 > H 3 OOH > a 3 PO 4 glucose > al > H 3 OOH > al 2 > a 3 PO 4 glucose > al > H 3 OOH > a 3 PO 4 > al 2 glucose > H 3 OOH > al > al 2 > a 3 PO 4 8. rrange the following species from left to right in order of increasing radius. a, Mg, F, a +, Mg 2+ F < Mg 2+ < a + < Mg < a a + < Mg 2+ < F < Mg < a a + < Mg 2+ < F < a < Mg Mg 2+ < a + < F < Mg < a Mg 2+ < Mg < a + < a < F 9. What is the [OH ] of a solution with a ph of 9.0? 0 5 M 0 9 M 0 4 M 0 7 M none of the above 0. Which of the following statements regarding the solubility of Mg(OH) 2 is correct? ph has no effect on the solubility of Mg(OH) 2. Mg(OH) 2 is less soluble at ph 4 than ph 7. Mg(OH) 2 is less soluble in 0. M Mgl 2 solution than in water. all of the above none of the above

4 HM09 ovember 2008 xample Multiple hoice Questions. When cells are placed into an isotonic solution (i.e. the solution and cell fluid have the same osmotic pressure): no exchange of water across the cell membrane occurs. water enters the cell faster than it leaves the cell. water leaves the cell faster than it enters the cell. water enters the cell at the same rate that it leaves the cell. ready exchange of solutes, but not water, occurs across the cell membrane. 2. What is the relationship between K c and K p for the following reaction? K p = K c (RT) 2 K c = K p (RT) 2 K c = K p K c = K p K c = K p RT (g) + (g) 2(g) 3. Histidine is an amino acid. The fully protonated form has the pk a values indicated below. pk a = 5.97 H H 2 pk a =.82 HOO H 2 H H 3 pk a = 9.7 Which one of the following is the predominant structure at ph 7.6? H H H H HOO H 2 H 2 H 2 H H 3 H H O 2 3 O 2 H H 3 H H H HOO H 2 H 2 H H 3 HOO H H 2

5 HM09 ovember 2008 xample Multiple hoice Questions 4. rrange the following M solutions in order of increasing ph. Hl KOH al 2 H 3 OOH a 3 PO 4 KOH < al 2 < a 3 PO 4 < H 3 OOH < Hl Hl < al 2 < H 3 OOH < KOH < a 3 PO 4 H 3 OOH < Hl < al 2 < KOH < a 3 PO 4 Hl < H 3 OOH < a 3 PO 4 < al 2 < KOH Hl < H 3 OOH < al 2 < a 3 PO 4 < KOH In answering questions 5-9, consider the following titration curve. 2 0 ph mount of solution added (ml) 5. Which one of the following combinations does the titration curve represent? ddition of a strong base to a weak acid ddition of a weak base to a strong acid ddition of a strong acid to a weak base ddition of a weak acid to a strong base ddition of a strong acid to a strong base 6. What is the value of the pk a that can be obtained from this titration curve? What is the ph of the solution at the point of maximum buffering? What is the ph of the solution at the equivalence point?

6 HM09 ovember 2008 xample Multiple hoice Questions 9. Which one of the following indicators would be most suitable for this titration? any acid/base indicator is suitable phenolphthalein (pk a = 9.6) cresol red (pk a = 8.3) methyl red (pk a = 5.) methyl yellow (pk a = 3.) 20. How many stereoisomers are possible for the complex [il 2 (en) 2 ]? en = ethylenediamine = H 2 H 2 H 2 H How many stereoisomers are possible for the complex [i(en) 3 ] 2+? en = ethylenediamine = H 2 H 2 H 2 H What is the solubility constant expression for Zn 3 (PO 4 ) 2? K sp = [Zn 2+ ][PO 3 4 ] K sp = [Zn 2+ ][2PO 3 4 ] K sp = [Zn 2+ ] 3 [PO 3 4 ] 2 K sp = [3Zn 2+ ] 3 [2PO 3 4 ] 2 K sp = [Zn 3+ ] 2 [PO 2 4 ] What is the solubility product constant expression for g 3 PO 4? K sp = [g + ][PO 3 4 ] K sp = [g + ][PO 3 4 ] 3 K sp = [g + ] 3 [PO 3 4 ] K sp = [3g + ] 3 [PO 3 4 ] K sp = 3[g + ][PO 3 4 ]

7 HM09 ovember 2008 xample Multiple hoice Questions 24. How would the concentration of Pb 2+ (aq) ions in equilibrium with PbI 2 (s) be affected if the concentration of I (aq) ions were doubled? no change increased by a factor of 2 decreased by a factor of 2 decreased by a factor of 4 decreased by a factor of Which one of the following is a coordination isomer of the complex salt, trans-[rl 2 (OH 2 ) 4 ]r? cis-[rl 2 (OH 2 ) 4 ]r trans-[rrl(oh 2 ) 4 ]l trans-[r r 2 (OH 2 ) 4 ]l trans-[rr 2 (OH 2 ) 4 ]l trans-[r(oh 2 ) 4 l 2 ]r 26. Which one of the following equations describes the enthalpy of combustion of glucose. 6 H 2 O 6 (s) 6(s) + 6H 2 O(l) 6 H 2 O 6 (s) 2 2 H 5 OH(l) + 2O 2 (g) 6 H 2 O 6 (s) 6(s) + 3O 2 (g) + 6H 2 (g) 6 H 2 O 6 (s) + 3O 2 (g) 6O 2 (g) + 6H 2 (g) 6 H 2 O 6 (s) + 6O 2 (g) 6O 2 (g) + 6H 2 O(g) Questions refer to the voltaic cell shown below. Voltmeter i Salt ridge u.0 M i 2+.0 M u 2+

8 HM09 ovember 2008 xample Multiple hoice Questions 27. What is the overall reaction occurring in this cell? There will be no spontaneous reaction. i 2+ (aq) + u(s) i(s) + u 2+ (aq) u 2+ (aq) + i(s) u(s) + i 2+ (aq) u 2+ (aq) + i 2+ (aq) + 4e u(s) + i(s) u(s) + i(s) u 2+ (aq) + i 2+ (aq) + 4e 28. What would be the value of cell at equilibrium? 0.58 V 0.34 V 0.24 V 0.0 V 0.00 V 29. What is the reading on the voltmeter when the half cells are first connected? 0.58 V 0.34 V 0.24 V 0.0 V 0.00 V 30. Which electrode is the anode and to which electrode do the electrons flow? The i electrode is the anode; electrons flow to the cathode. The u electrode is the anode; electrons flow to the cathode. The i electrode is the anode; electrons flow to the anode. The u electrode is the anode; electrons flow to the anode 3. Rank the following series of atoms in order of IRSIG electronegativity. O F P s < O < F < P < s F < O < < P < s s < P < < O < F s < P < < F < O F < < O < s < P

9 HM09 ovember 2008 xample Multiple hoice Questions 32. reaction has an activation energy of 40 kj mol and an overall energy change of 00 kj mol. In each of the potential energy diagrams shown below, the horizontal axis is the reaction coordinate and the vertical axis is potential energy in kj mol. Which potential energy diagram best describes this reaction? r e a c t a n t s p r o d u c t s r e a c t ants products reactants p r o d u c t s r e a c t a n t s p r o d u c t s r e a c t ants products 33. What is the missing particle for the following nuclear decay process? s a +? n 0 0 α 0 α 0 β 0 β 34. What isotope is produced by the α-decay of Rn? t Po Rn Fr t 35. Which one of the following statements about reaction rate is false? Reaction rate is the speed at which the reaction proceeds. Reaction rate is governed by the energy barrier between reactants and products. nzymes can accelerate the rate of a reaction. Reaction rates are not sensitive to temperature.

10 HM09 ovember 2008 xample Multiple hoice Questions 36. What isotope is produced by the α-decay of 99 Tc? 43 one Tc undergoes β decay 99 Mo b 4 99 Ru Rh 37. What is the oxidation state of Rh in the complex K 3 [Rh() 6 ]? +I +III +VI 0 III 38. What is the oxidation state of Tc in K 2 [TcO(ox) 2 ]? ox is the oxalate anion, 2 O II +III +IV +V +VI 39. solid pharmaceutical dispersed in a carrier gas is an example of which one of the following? a gel a foam an emulsion an aerosol 40. How many isomers are possible for the square planar complex [PtI 2 (H 3 ) 2 ]?

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