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 radioacti ve isotope with a half-life of 8 days. Given that radioactive decay is a firs t-order reaction, what fr action of the isotope would remain after 80 days? A 1 20 B 1 160 C 1 2଼ D 1 2ଵ଴ 11 Which is the correct statement about the following reaction? P(g) + Q(g) R(g) ∆H < 0 A Both the rate constant and equili brium constant wil l increase with increasing temperature. B The solid M will lower the activation energy of both forward and backward reactions. C Increasing temperature will lower the activation energy resulting only in a greater fraction of R molecules wit h energy greater than activation energy. D The activation energy of the forward reaction is equal to the activation energy of the backward reaction. M(s) 1395

12 13 The reac 2NO(g) + At differe condition three com below: Which of A There B There C There D A cat The value What can A Molar B The 25 C C The a temp D Wate ction betwe + F2(g) ⇌ ent times d ns inside t h mpounds in f the follow e was a de e was an in e was an in talyst was a e of the ion n be deduc r concentra ionic prod C. association erature inc er is no long een NO and 2 NOF(g) during the e he reaction n the equil ing statem ecrease in ncrease in ncrease in added at 7 nic product tempera 1 2 ced from th ation of H+ uct of wa t n of wate r creases. ger a neutr d F2 was st experimen n vessel. T librium mix ments is cor volume of volume of temperatu 7.5 min. t of water, ature / oC 0 10 25 his informa + ions decre ter decre a r molecule ral liquid a tudied by m ∆H < 0 nt, various The chang xture with t rrect? the reactio f the reacti ure at 10.0 Kw, varies Kw / mo 0.1 × 0.3 × 1.0 × tion? eases with ases by a s by hydr o t temperat mixing the changes w es in con c time are giv on vessel a on vessel min. with temp l2 dm–6 10–14 10–14 10–14 h decrease factor of ogen bon d tures below two gases were made centrations ven by the at 10.0 min at 7.5 min erature. e in temper 10 from 0 ding incre a w 25 C. s: e to the s of the e graph n. . rature. 0 C to ases as 1396

14 15 16 The grap 10 cm 3 of the end-p Which of and indic A 0.05 B 0.05 C 0.10 D 0.10 Use of th In many dioxide. By consi d dissolve i A lead When a q 5.63 g o f What is th A VO3 h shows th f 0.10 mol point for the the followi ator used f mol dm-3 e mol dm-3 e mol dm-3 e mol dm-3 e e Data Boo areas, ta p dering the in tap wate B quantity of f vanadium he formula B TPJC he change dm-3 sodiu e titration. ing contain for the titra ethanoic ac ethanoic a ethanoic a ethanoic a oklet is rele p water b e relevant er containin zinc f electricity m and 2.67 a of vanadiu VO C_2013_9647 in pH whe um hydroxi ns the corre ation? cid, screen acid, pheno acid, screen acid, pheno levant to th ecomes sli EƟ values ng carbon C y was pas s 7 g of oxy g um oxide? C 7_P1 en ethanoic ide. An ind ect concen ned methyl olphthalein ned methy olphthalein his question ghtly acid i , which m dioxide? iron sed throug gen were p ? V2O3 c acid is gr dicator is us ntration of e orange l orange n. c due to d etal will b D gh molten produced a D [Turn o radually ad sed to dete ethanoic a dissolved e least li k D magn vanadium at the elec D V3O2 over dded to ermine acid carbon kely to nesium oxide, trodes. 1397

17 Phosphorus is an element in the third period, Na to Ar, of the Periodic Table. What is true for phosphorus and none of the other elements in this period? A Phosphorus has the highest melting point of the elements in this period. B Phosphorus is the only element in this period that forms two acidic oxides. C Phosphorus is the only element in th is period with exactly four atoms in its molecule. D Phosphorus is the only element in this period whose chlorides react with water to form acidic solutions. 18 Which of the following statements about Group II elements from Mg to Ba is incorrect? A The melting point of the oxides increases down the group. B The reactivity of the elements with chlorine gas increases down the group. C The decomposition temperature of the nitrates increases down the group. D The volume of gases formed per gram of carbonate decomposed decreases down the group. 19 The equations for three reactions are given below: Cl2 (g) + H2S (g) → 2HCl (g) + S (s) SO2 (g) + 2H2S (g) → 2H2O (l) + 3S (s) Cl2 (g) + 2H2O (l) + SO2 (g) → 2HCl (aq) + H2SO4 (aq) Which is the correct order of strength of the three reacting gases as oxidising agents? Strongest Weakest A Chlorine Sulfur dioxide Hydrogen sulfide B Chlorine Hydrogen sulfide Sulfur dioxide C Hydrogen sulfide Sulfur dioxide Chlorine D Sulfur dioxide Hydrogen sulfide Chlorine 1398

TPJC_2013_9647_P1 [Turn over 20 What is the number of sp 2 and sp 3 carbon atoms in the structure given