TJC H2 CHEM P1 MCQ ANS KEY Prelim

This document consists of 17 printed pages. CHEMISTRY 9647/01 Paper 1 Multiple Choice Friday 23rd September 2011 1 hour Additional materials: Data Booklet Multiple Choice Answer Sheet READ THESE INSTRUCTIONS FIRST Do not open this booklet until you are told to do so. Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. Write your name, index number and CG on the Answer Sheet in the spaces 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 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.

2 9647/01/TJC Prelim 2011 [Turn over Section A For each question there are four possible answers, A, B, C and D. Choose the one you consider to be correct. 1 The Hofmann degradation is an example of a step-down reaction between an amide and a mixture of bromine and sodium hydroxide solution to form amines. The following shows an equation for the preparation of methylamine: CH3CONH2 + Br2 + 4NaOH  CH3NH2 + Na2CO3 + 2NaBr + 2H2O What is the mass of sodium hydroxide required for the reaction, given that 16.5 g of methylamine is produced? [Ar of C = 12.0; H = 1.0; N = 14.0; O = 16.0; Na = 23.0] A 5.3 g B 21.3 g C 66.2 g D 85.2 g 2 In an experiment, 0.0050 mol of a metallic salt reacted with 0.0025 mol of aqueous sodium sulfate(IV). The half-equation for oxidation of sulfate(IV) ion is shown below. SO3 2–(aq) + H2O(l)  SO4 2–(aq) + 2H+(aq) + 2e– If the original oxidation number of the metal in the salt was +3, what would be the new oxidation number of the metal? A 0 B +1 C +2 D +4 3 Which of the following has the largest bond angle? A PH3 B SiCl4 C IF2  D IF4  4 The numerical value for the Ksp of calcium phosphate, Ca 3(PO4)2, in water at 25 oC is 2.07 x 10⎯33. Determine the solubility of calcium phosphate. A 1.03 x 10⎯6 mol dm⎯3 B 3.42 x 10⎯7 mol dm⎯3 C 2.28 x 10⎯7 mol dm⎯3 D 1.14 x 10⎯7 mol dm⎯3

9647/01/TJC Prelim 2011 [Turn over 3 5 When 0.20 mol of hydrogen gas and 0.15 mol of iodine gas are heated at 723 K until equilibrium is established, the equilibrium mixture is found to contain 0.26 mol of hydrogen iodide. The equation for the reaction is as follows. H 2(g) + I2(g) 2HI(g) What is the correct expression for the equilibrium constant Kc? A 20 . 2 6 0.20 0.15   C   2 0.26 0.07 0.02 B  2 20 . 2 6 0.20 0.15   D   2 0.26 0.13 0.13 6 The table below shows the values of the ionic product of water, Kw, at two different temperatures. Temperature / oC Kw / mol2 dm6 25 62 1.00  1014 1.00  1013 Which of the following statements is correct for pure water? A The ionic dissociation of water is an exothermic process. B At 62 oC, pH = 14 − pOH. C At 62 oC, pH < pOH. D At 62 oC, pH < 7. 7 Consider the equation: 2SO2(g) + O2(g)  2SO3(g) ∆H = -199 kJ mol-1, ∆S = -190 J K-1 mol-1 Which of the following statements is correct? A In the formation of products, the system becomes more disordered. B The products are energetically less stable than the reactants. C As temperature increases, the reaction becomes more spontaneous. D The reaction is spontaneous under standard conditions.

9647/01/TJC Prelim 2011 [Turn over 4 8 Which of the following statements is true about the energy profile below? A F is the intermediate formed. B The enthalpy change of the reaction is E3 – E2. C The reaction is catalysed by a heterogenous catalyst. D E2 corresponds to the activation energy for the reaction in the second step. 9 The rate equation for the reaction, G + H + I  J + K is rate = k [H] [I]. Which of the following graphs is correct for the reaction, when I is in large excess? A C B D Energy Extent of reaction E1 E3 F E2 Rate 0 [H] Rate 0 [G] [H] 0 Time [I] 0 Time

9647/01/TJC Prelim 2011 [Turn over 5 10 Two cells are connected in series as shown in the diagram where L, M, N and O are electrodes. Which of the following correctly shows the products formed at each electrode? L M N O A O2 H 2 O 2 Fe 2+ B O2 Pb Cl2 H2 C Pb2+ H 2 Cl2 H2 D Pb2+ H 2 O 2 Fe 2+ 11 Given these standard electrode potentials Cu 2+(aq) + 2e– Cu(s) +0.34 V MnO 4 -(aq) + 8H+(aq) + 5e– ⇌ Mn2+(aq) + 4H2O(l) +1.52 V what would be the standard e.m.f. of the cell involving these two half-reactions and the polarity of the copper electrode? EӨ cell / V Polarity of the copper electrode A 1.86 + B 1.86 – C 1.18 + D 1.18 – 1 mol dm-3 HNO3(aq) 1 mol dm-3 FeCl3(aq) platinum lead L M N O

9647/01/TJC Prelim 2011 [Turn over 6 12 When 190 C of electricity is passed through a molten compound, about 0.21 g of a metal is deposited at the cathode. What could this metal be? A Magnesium C Silver B Copper D Iron 13 Figure 1 shows the first six ionisation energies of an element P. Figure 1 Figure 2 shows the second ionisation energies of eight consecutive elements (including P). Figure 2 With reference to Figure 2, which of the options, A, B, C or D, corresponds to the second ionisation energy of element P? Second Ionization Energy/ kJ mol-1 Atomic number A B C D 123456 Ionization Energy/ kJ mol-1 Electron removed

9647/01/TJC Prelim 2011 [Turn over 7 14 Which of the following statements regarding elements in Period 3 (i.e. sodium to chlorine) and their compounds is incorrect as the atomic number increases? A The oxides become increasingly acidic. B The chlorides become increasingly covalent. C The melting points of the elements generally increase. D The atomic radii of the elements generally decrease. 15 Unlike all other Group I nitrates, lithium nitrate decomposes on heating in the same way as Group II nitrates. Which one of the following equations represents the reaction that occurs when lithium nitrate is heated strongly? A 2LiNO 3 → 2LiNO2 + O2 B 2LiNO3 → Li2O + N2O + 2O2 C 2LiNO3 → Li2O2 + 2NO2 D 2LiNO3 → Li2O + 2NO2 + ½O2 16 The graphs given below show the trends in some properties related to the halogens X 2 (fluorine, chlorine, bromine and iodine) and their compounds down the group. Which of the following properties is not illustrated in the four graphs above? A pH of 0.1 mol dm–3 aqueous HX B X–X bond dissociation energy C reactivity of X2 D boiling point of X2

9647/01/TJC Prelim 2011 [Turn over 8 17 Which one of the following statements about the reaction below is false? [Cu(H2O)6]2+ + EDTA4– ⇌ [Cu(EDTA)]2– + 6H2O A Both [Cu(H2O)6]2+ and [Cu(EDTA)]2– are octahedral complexes. B There is a change in colour. C It is a redox reaction. D [Cu(EDTA)]2– is a more stable complex than [Cu(H2O)6]2+. 18 In which of the following mechanisms does the donation of an electron pair not take place? A Electrophilic substitution C Electrophilic addition B Nucleophilic addition D Free radical substitution 19 A student wishes to synthesise compound Q from benzene. NH2 Cl HO2C Compound Q Which of the following routes would give the maximum yield of Q? A Alkylation  nitration  chlorination  reduction  oxidation B Alkylation  nitration  oxidation  chlorination  reduction C Nitration  alkylation  reduction  chlorination  oxidation D Chlorination  nitration  reduction  alkylation  oxidation

9647/01/TJC Prelim 2011 [Turn over 9 20 Aspirin is a drug often used as an analgesic to relieve minor aches and pains, as an antipyretic to reduce fever, and as an anti-inflammatory medication. CO2H OCOCH3 As