TJC_H2_CHEM_P1_MCQ_ANS_KEY Prelim

This document consists of 17 printed pages. CHEMISTRY 9647/01 Paper 1 Multiple Choice Friday 23rd September 2011 1 hour Additional materials: Data Booklet Multiple Choice Answer Sheet READ THESE INSTRUCTIONS FIRST Do not open this booklet until you are told to do so. Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. Write your name, index number and CG on the Answer Sheet in the spaces provided. There are forty questions on this paper. Answer all questions. For each question, there are four possible answers A, B, C, and D. Choose the one you consider correct and record your choice in soft pencil on the separate Answer Sheet. Read the instructions on the Answer Sheet very carefully. Each correct answer will score one mark. A mark will not be deducted for a wrong answer. Any rough working should be done in this booklet.

2 9647/01/TJC Prelim 2011 [Turn over Section A For each question there are four possible answers, A, B, C and D. Choose the one you consider to be correct. 1 The Hofmann degradation is an example of a step-down reaction between an amide and a mixture of bromine and sodium hydroxide solution to form amines. The following shows an equation for the preparation of methylamine: CH3CONH2 + Br2 + 4NaOH  CH3NH2 + Na2CO3 + 2NaBr + 2H2O What is the mass of sodium hydroxide required for the reaction, given that 16.5 g of methylamine is produced? [Ar of C = 12.0; H = 1.0; N = 14.0; O = 16.0; Na = 23.0] A 5.3 g B 21.3 g C 66.2 g D 85.2 g 2 In an experiment, 0.0050 mol of a metallic salt reacted with 0.0025 mol of aqueous sodium sulfate(IV). The half-equation for oxidation of sulfate(IV) ion is shown below. SO3 2–(aq) + H2O(l)  SO4 2–(aq) + 2H+(aq) + 2e– If the original oxidation number of the metal in the salt was +3, what would be the new oxidation number of the metal? A 0 B +1 C +2 D +4 3 Which of the following has the largest bond angle? A PH3 B SiCl4 C IF2  D IF4  4 The numerical value for the Ksp of calcium phosphate, Ca 3(PO4)2, in water at 25 oC is 2.07 x 10⎯33. Determine the solubility of calcium phosphate. A 1.03 x 10⎯6 mol dm⎯3 B 3.42 x 10⎯7 mol dm⎯3 C 2.28 x 10⎯7 mol dm⎯3 D 1.14 x 10⎯7 mol dm⎯3

9647/01/TJC Prelim 2011 [Turn over 3 5 When 0.20 mol of hydrogen gas and 0.15 mol of iodine gas are heated at 723 K until equilibrium is established, the equilibrium mixture is found to contain 0.26 mol of hydrogen iodide. The equation for the reaction is as follows. H 2(g) + I2(g) 2HI(g) What is the correct expression for the equilibrium constant Kc? A 20 . 2 6 0.20 0.15   C   2 0.26 0.07 0.02 B  2 20 . 2 6 0.20 0.15   D   2 0.26 0.13 0.13 6 The table below shows the values of the ionic product of water, Kw, at two different temperatures. Temperature / oC Kw / mol2 dm6 25 62 1.00  1014 1.00  1013