Microsoft word - libs_task oachem 06_9701_01 2006.doc

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS Advanced Subsidiary Level and Advanced Level Additional Materials: Multiple Choice Answer Sheet Soft pencil (type B or HB is recommended) READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. Write your name, Centre number and candidate number on the Answer Sheet in the spaces provided unless this has been done for you. There forty questions on this paper. Answer all questions. For each question there are four possible 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 document consists of 14 printed pages and 2 blank pages. For each question there are four possible answers, A, B, C, and D. Choose the one you consider to be correct. 1 N2O4 is a poisonous gas. It can be disposed of safely by reaction with sodium hydroxide. N2O4(g) + 2NaOH(aq) → NaNO3(aq) + NaNO2(aq) + H2O(l) What is the minimum volume of 0.5 mol dm–3 NaOH(aq) needed to dispose of 0.02 mol of N2O4? 2 A sample of chlorine containing isotopes of mass numbers 35 and 37 was analysed in a 3 Gallium nitride, GaN, could revolutionise the design of electric light bulbs because only a small length used as a filament gives excellent light at low cost. Gallium nitride is an ionic compound containing the Ga3+ ion. What is the electron arrangement of the nitrogen ion in gallium nitride? 4 A radioactive isotope of thallium, 201 81 Tl, is used to assess damage in heart muscles after a heart A This isotope has a nucleon number of 120. B The number of electrons in one atom of this isotope is 81. C The number of neutrons in one atom of this isotope is 201. D 201 5 In which process are hydrogen bonds broken? 6 Which of the following least resembles an ideal gas? 7 The diagram shows part of the lattice structures of solids X and Y. [In X, What are the types of bonding present in X and Y? 8 In the conversion of compound X into compound Z, it was found that the reaction proceeded by way of compound Y, which could be isolated. The following steps were involved. 9 The nickel-cadmium rechargeable battery is based upon the following overall reaction. Cd + 2NiOOH + 4H2O → Cd(OH)2 + 2Ni(OH)2.H2O What is the oxidation number of nickel at the beginning and at the end of the reaction? 10 At a total pressure of 1.0 atm, dinitrogen tetraoxide is 50 % dissociated at a temperature of 60 C, What is the value of the equilibrium constant, K 11 Swimming pool water can be kept free of harmful bacteria by adding aqueous sodium chlorate(I), NaOCl. This reacts with water to produce HOCl molecules which kill bacteria. In bright sunshine, the OCl – ion is broken down by ultra-violet light. Which method would maintain the highest concentration of HOCl (aq)? 12 Which solid-line curve most accurately represents the distribution of molecular speeds in a gas at 500 K if the dotted-line curve represents the corresponding distribution for the same gas at 300 K? 13 In which pair is the radius of the second atom greater than that of the first atom? 14 The oxide and chloride of an element X are separately mixed with water. The two resulting solutions have the same effect on litmus. 15 Aluminium chloride sublimes at 178 o C. Which structure best represents the species in the vapour at this temperature? 16 Use of the Data Booklet is relevant to this question. What mass of solid residue can be obtained from the thermal decomposition of 4.10 g of anhydrous calcium nitrate? 17 What happens when chlorine is bubbled through aqueous potassium iodide? A Chlorine is oxidised to chloride ions. D Potassium iodide is reduced to iodine. 18 The emissions from a power station contain about 14 tonnes of SO2 per hour from the oxidation What is the most practical way of preventing the SO2 from being released into the atmosphere? A Cool the gases and the SO2 will liquefy and can be removed. C Pass the emissions through a bed of calcium oxide. D Pass the gases through concentrated sulphuric acid to dissolve the SO2. 19 The gaseous oxides of nitrogen have positive enthalpy changes of formation. Which factor is likely to make the most significant contribution to these enthalpy changes? A the high bond energy of the nitrogen molecule, N2 B the high electron affinity of nitrogen atoms C the high electron affinity of oxygen atoms D the similarity of the electronegativities of oxygen and nitrogen 20 A new industrial preparation of ethyl ethanoate has been developed using cheap sources of Which process is involved at some stage in this reaction sequence? How many chiral centres are present in the warfarin molecule? 22 The structures below show isomers of C6H12. In which pair are the members cis-trans isomers of each other? 23 Use of the Data Booklet is relevant to this question. In which reaction is the relative molecular mass of the organic product the largest? A bromoethane + aqueous sodium hydroxide B bromoethane + alcoholic sodium hydroxide 24 Light initiates the following reaction. alkane + chlorine → chloroalkane + hydrogen chloride What happens to chlorine in this photochemical reaction? A heterolytic fission to give an electrophile B homolytic fission to give an electrophile C heterolytic fission to give a free radical D homolytic fission to give a free radical 25 High-energy irradiation in the stratosphere produces radicals from chlorofluoroalkanes, commonly Which radical could result from this irradiation of CHFClCF2Cl? 26 Which reagent could detect the presence of alcohol in a petrol consisting mainly of a mixture of 27 Which alcohol may be oxidised to a product which reacts with 2,4-dinitrophenylhydrazine reagent 28 The first stage in the synthesis of antipyrine, a drug used in reducing fever, is the reaction What is the product Q of this first stage? 29 Aldehydes and ketones are carbonyl compounds. Which of them react both with NaBH4 and with Tollens’ reagent? 30 Which compound is a product of the hydrolysis of CH3CO2C3H7 by boiling aqueous sodium For each of the questions in this section, one or more of the three numbered statements 1 to 3 may be correct. Decide whether each of the statements is or is not correct (you may find it helpful to put a tick against the statements that you consider to be correct). The responses A to D should be selected on the basis of No other combination of statements is used as a correct response. 31 The Group IV elements carbon, silicon and germanium all exist in a diamond structure. The bond lengths in these structures are given below. bond length X–X / nm 0.154 0.234 0.244 Why does the bond length increase down the group? 1 Orbital overlap decreases down the group. 2 Atomic radius increases down the group. 3 Nuclear charge increases down the group. 32 Sodium ions can be formed from sodium atoms. Which quantities are required to calculate the enthalpy change of formation of gaseous sodium ions? 1 enthalpy change of atomisation of sodium 3 enthalpy change of formation of sodium The responses A to D should be selected on the basis of No other combination of statements is used as a correct response. 33 Hydrazine, N2H4, is widely used as a rocket fuel because it reacts with oxygen as shown, producing ‘environmentally friendly’ gases. Despite its use as a rocket fuel, hydrazine does not spontaneously burn in oxygen. Why does hydrazine not burn spontaneously? • does not conduct electricity when in a liquid state, • when added to water produces a solution that readily conducts electricity. 35 Hydroxyapatite, a basic calcium phosphate, Ca(OH)2.3Ca3(PO4)2, is the mineral found in bone. In older people, calcium ions can be lost from the hydroxyapatite, weakening the bone structure. In such cases, strontium salts are administered to strengthen the bone. The strontium ions replace the lost calcium ions in the hydroxyapatite. 1 Strontium ions are nearly the same size as calcium ions and so may easily replace them in 2 Strontium hydroxide is less soluble than calcium hydroxide and so will precipitate better in 3 There is ionic, covalent and metallic bonding in hydroxyapatite which gives it strength. 36 Ammonia and chlorine react in the gas phase. 3 The oxidation number of the hydrogen changes. 37 In which pairs are the members stereoisomers of each other? The responses A to D should be selected on the basis of No other combination of statements is used as a correct response. 38 Deuterium, D, is the 2H isotope of hydrogen. DBr has the same chemical properties as HBr. Which compounds could be made by the reaction of DBr with another compound in a single reaction? 39 How can the rate of reaction between ethanal and aqueous hydrogen cyanide be increased? 3 by the addition of a small quantity of aqueous sodium cyanide 40 Which statements about lactic acid, CH3CH(OH)CO2H, are correct? 2 Two hydrogen atoms per lactic acid molecule can be involved in hydrogen bonding. 3 Lactic acid would form an aldehyde when oxidised by acidified potassium dichromate(VI). Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will be pleased to make amends at the earliest possible opportunity. University of Cambridge International Examinations is part of the University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge.

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