DHS H2 CHEM P1

2 BLANK P AGE [Turn Over

3 Section A For each question, there ar e four possible answers A, B, C, and D. Choos e the one you consider to be correct. 1 When 10.0 cm3 of a 0.10 mol dm–3 solution of alkali metal salt MXO3 was reduced with an excess of acidified potassium iodide solution, the resulting iodine required 60.0 cm 3 of 0.10 mol dm –3 sodium thiosulfate solution for its reduction. The anion could be reduced to A XO2 B XO2– C XO– D X– 2 10 cm3 of a hydrocarbon is mixed with 100 cm 3 of oxygen gas which is in excess. The mixture is exploded and after it is cooled to room temperature, the residual gase s occupy a volume of 80 cm 3. Upon passing the gases through potassium hydroxide, th is volume decreases to 50 cm3. What is the formula of the unknown hydrocarbon? A C3H6 B C3H8 C C4H8 D C4H10 [Turn Over

4 3 The use of Data Booklet is relevant to this question. The successive ionis ation energies, in kJ mol –1, of an element X are given below. 870 1800 3000 3600 5800 7000 13200 What is element X? A 33As B 53I C 8O D 52Te 4 A 10.0 dm 3 sample of oxygen at a pressure of 250 kPa and 3.0 dm 3 sample of nitrogen at a pressure of 500 kPa are introduced into a 2.5 dm 3 vessel at room temperature. What is the total pressure in the vessel? A 750 kPa B 1200 kPa C 1600 kPa D 1950 kPa 5 Given that the standard ent halpy change of combustion of but-1-ene and ethene are p and q kJ mol–1 respectively. What is the standard enthalpy change of the reaction: 2C2H4(g)  C4H8(g)? A 2q – p kJ mol–1 B (p + q)/2 kJ mol–1 C q – 2p kJ mol–1 D (q – p)/2 kJ mol–1 [Turn Over

5 6 The data below refers to the st andard molar enthalpy changes of combustion of some members of the alkanes. Alkane Hc /kJ mol–1 CH4 –890 C2H6 –1560 C3H8 –2220 C4H10 –2880 C5H12 –3510 C6H14 –4190 Another alkane X has a standard enthalpy c hange of combustion of –6780 kJ mol –1. The formula of X is likely to be A C9H20 B C10H22 C C11H24 D C12H26 7 The data below refers to the radii and charges of six ions. Ion P2+ Q + R + T 2– U – V – Radius/nm 0.16 0.19 0.15 0.16 0.19 0.15 PT, QU and RV are ionic solids of the same lattice structure. Which one of the following gives the correct order of their la ttice energies with the lowest numerical value first? A PT RV QU B PT QU RV C RV QU PT D QU RV PT [Turn Over

6 8 In the presence of ultraviolet light, the “inert” xenon gas will react with fluorine gas to produce XeF4 according to the equation, Xe (g) + 2 F2 (g) XeF4 (s) What is the correct equilibrium constant Kc? A B C D 9 The decomposition of dinitrogen pentoxide N 2O5 is found to be first order with respect to the concentration of N 2O5. Which one of the following graphs confirms the results? A Rate of decomposition of N2O5 [N2O5] 0 B Rate of decomposition of N2O5 [N2O5] 0 C Rate of decomposition of N2O5 [N2O5] 0 D Rate of decomposition of N2O5 [N2O5] 0 [Turn Over

7 10 What is the pH of the final soluti on formed by mixing equal v olumes of two separate portions of dilute sulfuric acid of pH 2.0 and pH 4.0? A 2.3 B 2.6 C 3.0 D 3.6 11 Hydrogen iodide is not pr epared by the addition of concentrated sulfuric acid to solid sodium iodide. This can be best explained by the fact that A Hydrogen iodide is not displaced by sulfuric acid. B Iodide ions are oxidised to iodine. C Sodium sulfide is formed as an impurity. D Hydrogen iodide is less volatile than concentrated sulfuric acid. 12 Which one of the following gives t he correct definition of an acid according to the Bronsted-Lowry theory? A It dissociates in water to give H+(aq) ions. B It is a proton donor. C It is a proton acceptor. D It is an electron donor. [Turn Over

8 13 The graph below shows the v ariation in the boiling points for eight consecutive elements in the Period Table, all wit h atomic numbers from 10 to 20. The letters do not represent any element in the Periodic Table. Which of the following can be deduced from the graph above? A Element H forms an acidic oxide only. B Element K does not conduct electricity. C Element G can exist in two allotropic forms. D Element E and beryllium are in the same group. Boiling Point F 14 A typical chemical reaction is acid catalysed, and the reaction is first order with respect to t he hydrogen ion. If all other conditions are kept constant, what is the ratio of rate of reaction at pH 3 rate of reaction at pH 1 A 0.01 B 0.33 C 1 D 3 ? Atomic number K G E L H I J [Turn Over

9 15 Consider the following four compounds: (I) (CH3)3CH (II) CH 3CH2CH2OH (III) CH 3CH2CH2SH (IV) CH 3CH2CH2CH3 What is the order of increasing boiling point of the compounds? A I, IV, III, II B I, IV, II, III C II, III, IV, I D III, II, IV, I 16 Which one of the follo wing statements would not be expected for Group II elements or its compounds? A Barium sulfate has numerically smaller lattice energy than magnesium sulfate. B Beryllium forms compound with the least covalent character. C Barium oxide in water produces an equilibrium with high Kb. D The heating of nitrates of Group II compounds will result in an increase in entropy. 17 Which one of the follo wing statements about Group II elements is correct? A The reactivity with cold water decrease down the Group. B The charge density of Group II cations increases from Be to Ba. C The minimum temperature for the thermal decomposition of Group II nitrates increases down the Group. D The melting point of Group II carbonates decrease down the Group due to the decreasing polarising power of cations. [Turn Over

10 18 Which one of the follo wing statement is true of vanadium an d its compound? A The maximum oxidation state of vanadium is found in VO2+. B V2O5 is used as a catalyst in the manufacture of ammonia. C Zinc reduces VO2 +(aq) to V2+(aq). D Vanadium is less dense than calcium. 19 Which of the following statement describes a phenomenon which can be explained by intermolecular hydrogen bonding? A Ammonia is very soluble in water. B CH3OCH3 (Mr = 46) has a higher boiling point than CH 3CH2CH3 (Mr = 44). C Hydrogen chloride forms an acidic solution when dissolved in water. D The boiling points of the alkanes increase with increasing relative molecular mass. 20 A compound Z has the formula Cr(H 2O)6Cl3 and a relative formula mass of 266. A 10 cm 3 solution containing 26.6 g dm –3 of Z requires 20 cm 3 of 0.1 mol dm–3 AgNO3 to completely precipitate the chloride ions. Whi