ACJC H2 Chem 2013 Prelim P1 QP

© ACJC 2013 9647/01/Prelim/13 [Turn over 2 Section A For each question there are four possible answers, A, B, C, and D. Choose the one you consider to be correct. 1 10 cm3 of a hydrocarbon was mixed with 100 cm 3 of oxygen gas which was in excess. After explosion and cooling, the gaseous mixture occupied a volume of 80 cm 3. After absorption by aqueous potassium hydroxide, the volume decreased to 50 cm3. What is the formula of the unknown hydrocarbon? A C3H6 B C3H8 C C4H8 D C4H10 2 Ethanenitrile, CH 3CN was boiled with NaOH and the NH 3 gas evolved was passed into 50 cm 3 of 1.00 mol dm -3 of HC l. The excess acid required 26.00 cm3 of 1.00 mol dm-3 NaOH solution for complete neutralisation. What was the mass of ethanenitrile used? A 0.492 g B 0.984 g C 1.07 g D 1.97 g 3 For a given mass of an ideal gas, which one of the following graphs displays a different shape from the rest? A PV against V (at constant T) B PV against P (at constant T) C T V against T (at constant P) D density 1 against T (at constant P) 237

© ACJC 2013 9647/01/Prelim/13 [Turn over 3 4 Xofigo®, containing the radioactive isotope, Ra223 88 , had received United States FDA approval for the treatment of cancer in patients. Ra223 88 decays to give only an element X and a high energy α-particle ( He4 2 ); the latter targets the cancer cells. Ra223 88  X + He4 2 What is the number of neutrons present in element X? A 86 B 133 C 135 D 219 5 Phosphorus oxides exist in many different intermediate forms. Two forms of phosphorus oxides, P4O9 and P4O10, are shown above. Which one of the following statements is true? A The phosphorus atoms of both oxides can act as ligands. B The phosphorus atoms of both oxides have the same oxidation state. C The phosphorus atoms of both oxides do not have lone pair of electrons D The phosphorus atoms of both oxides have electron pairs that are arranged in tetrahedral shape. P O P O PO O O OP O O O P O P O PO O O OP O O O O P4O9 P4O10 238

© ACJC 2013 9647/01/Prelim/13 [Turn over 4 6 Which statement about AlCl3 is correct? A AlCl3 is pyramidal. B AlCl3 has a higher melting point than Al2O3. C Al2Cl6 dimer contains two co-ordinate bonds. D AlCl3 catalyst acts as an electron pair donor in the acylation of benzene. 7 Consider the equation: 2SO2(g) + O2(g) → 2SO3(g) where ∆H = -199 kJ mol-1 and ∆S = -190 J K-1 mol-1. Which of the following statements is correct? A As the reaction proceeds, the system becomes more disorderly. B The products are energetically less stable than the reactants. C As temperature increases, the change in Gibbs free energy becomes more negative. D The reaction is spontaneous under standard conditions. 8 Consider the mechanism of the hydrolysis of 2-methyl-2-bromopropane (RBr) by hydroxide