TPJC H2 Chem 2013 Prelim P1 QP _ Soln

1 TPJC 2013 H2 Chemistry Section A For each question there are four possible answers, A, B, C and D. Choose the one you consider to be correct. 1 Use of the Data Booklet is relevant to this question. How many molecules are present in 1 cm 3 of oxygen gas under room conditions? A 1 x 24000 6.02 x 1023 B 1 x 6.02 x 1023 24000 C 6.02 x 1023 x 24000 1 x 1000 D 1 x 6.02 x 1023 x 32 2 10 cm3 of 0.2 mol dm-3 K2XO4 completely reacts with 40 cm3 of 0.1 mol dm-3 iron(II) sulfate solution. If Fe 2+ is oxidised to Fe3+ by K2XO4, what is the final oxidation state of X? A +2 B +3 C +4 D +5 3 Which of the following ions would undergo the greatest deflection in an electric field? A 16O2+ B 16O18O+ C 16O18O2+ D 18O2+ 4 Which of the following consists of species which are all planar? A CO3 2– , SO3 2– and benzene B Al2Cl6 , SOCl2 and methanal C NO3 – , XeF4 and ethanal D BCl3 , ICl4 – and chlorobenzene 1393

5 The value of pV is plotted against p at the same temperature for four gases, where p is the pressure and V is the volume of the gas. Which of the following represent the possible identities of Gases 1 to 4? Gas 1 Gas 2 Gas 3 Gas 4 A Ne CH 3F HF H 2O B Ne HF CH 3F H 2O C HF H 2O CH 3F Ne D H2O HF CH 3F Ne 6 The table gives the successive ionisation energies for an element X. 1 st 2 nd 3 rd 4 th 5 th 6 th Ionisation energy/ kJmol -1 950 1800 2700 4800 6000 12300 What could be the formula of the chloride of X? A XCl B XCl2 C XCl3 D XCl4 7 The table shows the charge and radius of each of the six ions. ion J + L + M 2+ X - Y - Z 2- radius/nm 0.14 0.18 0.15 0.14 0.18 0.15 The ionic solids JX, LY, and MZ have the same lattice type. What is the order of their lattice ener gies starting from the most exothermic first? A JX, MZ, LY B LY, JX, MZ C MZ, JX, LY D MZ, LY, JX pV p Gas 4 Gas 3 Gas 2 Gas 1 1394

TPJC_2013_9647_P1 [Turn over 8 Dinitrogen oxide, N=N=O, burns in ethyne, H‒C≡C‒H, in the gaseous phase to produce water vapour, carbon diox ide and nitrogen gases as the only products. 5 N2O(g) + C2H2(g)  H2O(g) + 2 CO2(g) + 5 N2(g) H = -1668 kJ mol-1 Assuming N=N bond energy in dinitrogen oxide is +418 kJ mol -1, what is the nitrogen-oxygen bond energy in dinitrogen oxide in kJ mol-1? A 382 B 594 C 686 D 1350 9 Which of the following statements about the spontaneity of the gas-phase reaction shown is true at 25 °C? 2 O=N–Cl(g)  2 N=O(g) + Cl 2(g) A The reaction cannot be spontaneous. B The reaction will be spontaneous r egardless of the magnitude of H and S. C The reaction will be spontaneous only if the magnitude of  H is large enough to overcome the unfavorable entropy change. D The reaction will be spontaneous only if the magnitude of S is large enough to overcome the unfavorable enthalpy change. 10 Iodine-131 is a radi