NJC H2 Chem 2013 Prelim P1 QP

1 NJC/H2 Chem/01/2013 [Turn over NATIONAL JUNIOR COLLEGE SH2 PRELIMINARY EXAM Higher 2 CANDIDATE NAME SUBJECT CLASS REGISTRATION NUMBER CHEMISTRY Paper 1 Multiple Choice Additional Materials: Multiple Choice Answer Sheet Data Booklet 9647/01 Thu 19 Sept 2013 1 hour READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. Write your name, subject class and registration number on the Answer Sheet in the spaces provided unless this has been done for you. There are 40 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. This paper consists of 19 printed pages and 0 blank page. 84

2 NJC/H2 Chem/01/2013 [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 Which one of the following represents the configuration of the three electrons of highest energy for the ground state of an element in group III? A 1s2 2s1 B 1s1 2s1 2p1 C 2s1 2p2 D 4s2 4p1 2 The first ionisation energies of twenty successive elements in the Periodic Table are represented in the graph. The letters given are not the normal symbols for these elements. Which statement about the elements and their compounds in this graph is not true? A Oxide and hydroxide of element M are amphoteric. B Oxide of element F has a giant covalent lattice structure. C Elements B, J and R are in Group 0 of the Periodic Table. D The second ionisation energy of K is larger than the second ionisation energy of L. first ionisation energy /kJ mol1 85

3 NJC/H2 Chem/01/2013 [Turn over 3 In an experiment, a beam of protons was passed through an electric field of constant strength. Analysis of the deflection occurring at the electric field region revealed an angle of deflection of 12° towards the negative plate. Under identical conditions, a beam of particles, Q, each having 24 times the mass of a proton, was deflected by an angle of 1o towards the positive plate. What is the overall charge on a particle of Q? A +2 B +3 C –3 D –2 4 Use of the Data Booklet is relevant to this question. A typical solid fertiliser for use with household plants and shrubs contains the elements N, P, and K in the ratio of 15 g : 30 g : 15 g per 100 g of fertiliser. The recommended usage of fertiliser is 14 g of fertiliser per 5 dm3 of water. What is the concentration of nitrogen atoms in this solution? A 0.03 mol dm–3 B 0.05 mol dm–3 C 0.42 mol dm–3 D 0.75 mol dm–3 12o protons 86

4 NJC/H2 Chem/01/2013 [Turn over 5 0.200 mol of a hydrocarbon undergo complete combustion to give 35.2 g of carbon dioxide and 14.4 g of water as the only products. What is the molecular formula of the hydrocarbon? A C2H4 B C2H6 C C4H4 D C4H8 6 The ions P 3–, S2– and Cl– have radii 0.212nm, 0.184nm and 0.181nm respectively. Which one of the following correctly explains the decreases in radius going from P 3– to Cl–? A An increase in both the total number of electrons and the nuclear charge B An increase in the total number of electrons with the nuclear charge remaining constant C A constant total number of electrons and an increase in the nuclear charge D A decrease in the total number of electrons with the nuclear charge remaining constant 7 Which of the following species does not have a bond angle of 120 o around the central atom(s)? A AlCl3 B CH3 + C PH3 D N2O4 8 In which process are hydrogen bonds broken? A 2H2O(l) → 2H2(g) + O2(g) B CH3CH2OH(l) → CH3CH2OH(g) C NH3(aq) + H2O(l) → NH4 +(aq) + OH‒(aq) D CH3COOH(aq) + NaOH(aq) → CH3COONa(aq) + H2O(l) 87

5 NJC/H2 Chem/01/2013 [Turn over 9 The equation below represents the combination of gaseous atoms of non-metal X and of hydrogen to form gaseous X2H6 molecules. 2 X(g) + 6 H(g) → X2H6(g) ∆H = –2775 kJ mol–1 The bond energy of an X–H bond is 395 kJ mol–1. What is the bond dissociation energy of an X–X bond? A –405.0 kJ mol–1 B –202.5 kJ mol–1 C +202.5 kJ mol–1 D +405.0 kJ mol–1 10 Which of the following statements about lattice structures is correct? A The lattice energy of an ionic crystal tends to be large if the sizes of the two types of ions involved are small. B The particles occupying lattice sites may be atoms or ions but not molecules. C The forces holding the lattice together are so strong that the particles occupying lattice sites are held stationary. D The lattice energy of an ionic crystal is always larger than that of a metal. 88

6 NJC/H2 Chem/01/2013 [Turn over 11 The diagram shows the Born-Haber cycle for the formation of magnesium fluoride. Mg(s) + F2(g) MgF2(s) Which of the following represents the correct energy changes, ∆H1 and ∆H2? ∆H1 ∆H2 A Hatm of Mg + 1st and 2nd E.A of Mg 2Hatm of F2 + 2(1st I.E of F) B Hatm of Mg + 1st and 2nd I.E of Mg 2(B.E of F2) + 2(1st E.A of F) C Hatm of Mg + 1st and 2nd I.E of Mg 2Hatm of F2 + 2(1st I.E of F) D Hatm of Mg + 1st and 2nd I.E of Mg B.E of F2 + 2(1st E.A of F) 12 25 % of a solution of ethanoic acid was converted to ethanoate ions by reaction with sodium hydroxide solution at 25 oC. What is the K a of ethanoic acid at 25 oC given that the pH of the solution was found to be 4.28? A 1.57 × 10‒4 B 1.31 × 10‒5 C 1.75 × 10‒5 D 5.24 × 10‒5 ∆H2 ∆H1 2F(g) + Mg2+(g) Hatm : Enthalpy change of atomization I.E : Ionisation energy E.A : Electron Affinity B.E : Bond energy 89

7 NJC/H2 Chem/01/2013 [Turn over 13 The solubility of iron(II) carbonate in water at 25 oC is 5.59 × 10‒6 mol dm‒3. What is the numerical value of the solubility product for iron( II) carbonate when dissolved in a 0.01 mol dm‒3 solution of iron(II) chloride at 25 oC? A 5.59 × 10‒8 B 5.59 × 10‒10 C 3.12 × 10‒9 D 3.12 × 10‒11 14 The following data is obtained during the first order thermal decomposition of 2A(g)  B(g) + C(s) at constant volume and temperature. Time Total pressure in Pascal At the end of 10 minutes of reaction 600 After completion of reaction 400 What is the rate constant for this reaction in min1? A cannot be determined due to insufficient data B 0.0346 C 0.0693 D 0.138 90

8 NJC/H2 Chem/01/2013 [Turn over 15 The curve Y and the value Ea re