NYJC H2 Chem Prelim 08 P1

NANYANG JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 2 CHEMISTRY 9746/01 Paper 1 Multiple Choice 17 September 2008 1 hour Additional Materials: Multiple Choice Answer Sheet Data Booklet READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. Write your name, class and tutor’s name on the Answer Sheet in the spaces provided unless this has been done for you. 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 you 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 18 printed pages and 0 blank page. [Turn over

2 Section A For each question there are four possible answers, A, B, C and D. Choose the one you consider to be correct. 1 In an attempt to establish the formula of an oxide of nitrogen, a known volume of the pure gas was mixed with hydrogen and pass ed over a catalyst at a suitable temperature. 100% conversion of the ox ide to ammonia and water was shown to have taken place. N xOy xNH3 + yH2O H2(g) 2400 cm 3 of nitrogen oxide measured at room temperature and pressure produced 7.20 g of water. The ammonia produced was neutralized by 200 cm3 of 1.0 mol dm−3 of HCl. What is the oxidation number of the nitrogen in the nitrogen oxide? A +1 B +2 C +3 D +4 2 Which one of the following ions has more electrons than protons, and more protons than neutrons? [D= ] H2 1 A D − B He + C OH − D D 3O+ 3 Which one of the following molecules is planar? A NF 3 B C 2Cl4 C SF 6 D cyclohexane, C 6H12 H2 Chemistry 9746/01 NYJC J2/08 PX

3 4 Pyrogallol is a white crystalline powder and a powerful reducing agent that is used to absorb oxygen. When 30 cm3 of a gaseous hydrocarbon is exploded with 200 cm3 of oxygen, there is a contraction of 90 cm 3. On further treatment with alkaline pyrogallol, there was a reduction of 20 cm3. What is the molecular formula of t he hydrocarbon? (All volumes are measured at room temperature pressure). A C 4H8 B C 4H10 C C 3H8 D C 3H6 5 The enthalpy change when solid sodium hydroxide dissolves in water is − 44.4 kJ mol−1. 250 g of water is placed in a coffee-cup calorimeter containing 13.9 g of sodium hydroxide. If the solution has the same specific heat capacit y as liquid water, what is the rise in temperature of the solution? A 18 4 250 4 44 9 13 . . . × × K B 310 4 44 9 13 18 4 250 ×× × . . . K C 313.9 44.4 10 40 250 4.18 ×× ×× K D 18 4 9 263 10 4 44 9 133 . . . . × × × K 6 The distribution of the number of molecules with energy E is given in the sketch for two temperatures, T1 and a higher temperature T2. The letters P, Q, R refer to the separate and differently shaded areas. The activation energy is marked on the energy axis. Legend Number of molecules with energy E T2 T1 region P region Q region R activation energy energy E Which expression gives the fraction of the molecules present which have at least the activation energy at the higher temperature T2? A Q P B QR P + C QR PQ + + D QR PQR + ++ H2 Chemistry 9746/01 NYJC J2/08 PX [Turn over

4 7 Two equilibria are shown below. Reaction I: 2NO2(g) 2NO(g) + O2(g) Reaction II: NO(g) + 2 1 O2(g) NO2(g) The numerical value of Kc for reaction I is 0.36. Under the same conditions, what is the numerical value of Kc for reaction II? A 0.18 B 1.7 C 2.8 D 5.6 8 The table shows the data on two acid-base indicators. colour change indicator approximate pH range in acid in alkali bromocresol green 3.8 – 5.5 yellow blue phenol red 6.8 – 8.5 yellow red What conclusion can be drawn about a so lution in which bromocresol green is blue and phenol red is yellow? A It is weakly acidic. B It is strongly acidic. C It is neutral. D It is weakly alkaline. 9 A sample of 1 mol of ethanoic acid is dilu ted at constant temperature to a volume V. Which diagram shows how the acid dissociation constant, Ka, varies with V? A B C D Ka Ka V V Ka Ka V V H2 Chemistry 9746/01 NYJC J2/08 PX

5 10 The use of the Data Booklet is relevant to this question. What will be observed when a few drops of acidified aqueous hydrogen peroxide are added to an excess of aqueous potassium iodide? A The solution turns brown and effervescence occurs. B The solution turns brown without effervescence. C The solution does not change colour and effervescence occurs. D The solution turns purple and effervescence occurs. 11 When a large current was pa ssed through acidified aqueous copper (II) sulphate, there was simultaneous liberat ion, at the cathode, of x mol of copper and y dm3 of hydrogen (measured at s.t.p.). How many moles of electrons passed through the solution? A 22.4 yx + B 11.2 yx + C 2 11.2 yx + D 2 22.4 yx + 12 Which of the following statements about the Group VII compounds is correct? A The hydration energy of the gaseous halide ions becomes more negative down the group. B The K sp values of the silver halides decrease down the group. C The lattice energy of the silver halides becomes more exothermic down the group. D The halogens increase in oxidising power down the group. 13 In which of the following pairs is the ioni c radius of the first ion smaller than that of the second ion? A Na +, Mg2+ B Mg 2+, S2− C F −, Na+ D P 3−, S2− 14 Iron has a proton (ato mic) number of 26. What is the electronic configuration of the iron cation which can form the complex ion [Fe(H2O)5SCN]2+? [[Ar] ≡ 1s2 2s2 2p6 3s2 3p6] A [Ar] 3d3 4s2 B [Ar] 3d4 4s2 C [Ar] 3d5 4s0 D [Ar] 3d6 4s0 H2 Chemistry 9746/01 NYJC J2/08 PX [Turn over

6 15 Esters can be converted to alcohols us ing lithium aluminium hydride followed by the addition of water. C O O C C H O H C2H5 + OC 2H5 + OC 2H5 CH OH H + HO C 2H5 O H H H2O H Which of the following reaction does not occur in this process? A hydrogenation B hydrolysis C nucleophilic addition D nucleophilic substitution 16 In the free radical substitution of 2- methylbutane with bromine, a mixture of mono-brominated compounds were obtained. What is the statistical ratio of the two compounds with the highest yields? A 1 : 1 B 1 : 2 C 1 : 3 D 1 : 6 H2 Chemistry 9746/01 NYJC J2/08 PX

7 17 Which compound could be formed by t he action of bromine on an alkene of molecular formula C4H8? A CBr H H C H C H H H C H H Br B C H H H C H C Br H H C H H Br C C H H H C Br C C H H H H H Br D C H H H C H C C H H H H Br Br 18 Oxidation of an alkene gives a diol; further oxidation gives a diketone. What is the formula of the alkene? A (CH3)2C=C(CH3)2 B CH 3CH=C(CH3)2 C C 6H5CH=CHC6H5 D (C 6H5)2C=CHCH3 19 Nitrobenzene is a yellow liquid with the smell of almonds. It may be prepared by heating a mixture of benzene, concentra ted nitric acid and concentrated sulphuric acid under reflux. Why is concentrated sulphuric acid used? + HNO3 NO2 + H2O A It acts as a dehydrating agent to remove the water produced. B It donates protons to nitric acid, thus forming NO 2 + ions. C It removes protons from ni tric acid, thus forming NO2 − ions. D It acts as a catalyst to speed up the reaction. H2 Chemistry 9746/01 NYJC J2/08 PX [Turn over

8 20 The reaction between boiling methylbenzene and chlorine takes place in a number of steps to give several products. Which of the following could not be one of the steps? A CHCl + C l2 → CHCl2 + C l • B CH2 + HCl → CH2Cl