MI H2 Chem 2012 Prelim P1 Soln

2 Answer all questions on the OMR form provided (40 Marks) For each question, there are four possible answers, A, B, C and D. Choose the one you consider correct. 1 Zn reacts with VO3- ions to give Vn+. 3.9 g of Zn was required to react completely with 40.0 cm3 of 1.0 mol dm-3 of KVO3. What is the value of n? A 1 C 3 B 2 D 4 2 In which of the following pairs do the species have different shapes? A AlCl3 and CO32- B NH4+ and CH4 C NH3 and H3O+ D SeF4 and SO42- 3 The following graph shows how ionic radius changes across Period 3 for seven elements. A The sharp increase in ionic radius between the 4th and 5th element is due to an increase in the number of principal quantum shells. B There is a decrease in ionic radius for the first 4 elements in Period 3 due to decreasing shielding effect. C There is a decrease in ionic radius for the last 3 elements due to decreasing proton to electron ratio. D The first 4 elements form anions and hence have lower ionic radii than the last 3 elements which form cations. 11 12 13 14 15 16 17 Atomic Number Unknown PropertyIonic radius

[Turn over 3 4 In which of the following reactions is the acid acting as an oxidant? A KBr + H3PO4 ® HBr + KH2PO4 B MgO + H2SO4 ® MgSO4 + H2O C 12HClO4 + P4O10 ® 6Cl2O7 + 4H3PO4 D Cu + 4HNO3 ® Cu(NO3)2 + 2H2O + 2NO2 5 A 1dm3 flask containing helium at 2 kPa pressure is connected (at constant temperature) to a 2 dm3 flask containing neon at 1 kPa pressure. What is the final pressure after connection? A 4 3 kPa B 3 2 kPa C 5 3 kPa D 2 kPa 6 The use of the Data Booklet is relevant to this question. Phosphorus, P4, has the following molecular structure: P P P P Imagine that nitrogen were to form a similar molecule N 4 shown in the reaction below: 2N2(g) ® N4(g) What would be the value of ΔH (in kJ mol–1) for the above reaction? A 1028 B 1348 C 1954 D 2628

4 7 Which gas shows the greatest deviation from ideal gas behavior? A HCl B He C CH4 D N2 8 The use of the data booklet is relevant to this question. In many areas, tap water is slightly acidic due to dissolved carbon dioxide. Which metal will not be dissolved by tap water containing carbon dioxide? A Cr C Fe B Cu D Pb 9 Which of the following mixtures is not an acid/conjugate base pair? A H2O/OH- C NaH/Na B H2PO4-/HPO42- D NH3/NH2- 10 Which of the following pairs of solutions would form an acidic buffer when mixed? A HCN and NaCN B HNO3 and NaNO3 C NaOH and NaCl D HCl and NaOH 11 Bleaching solutions are manufactured by dissolving chlorine gas in sodium hydroxide solution to give the following reaction. Cl2 (g) + 2OH- (aq) OCl- (aq) + Cl- (aq) + H2O (l) Users are warned not to mix the bleach with other cleaning solutions to prevent evolution of hazardous chlorine gas. Which of the following actions will lead to liberation of chlorine gas? A