CJC_H2_CHEM_P1 Prelim

CATHOLIC JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATIONS Higher 2 CHEMISTRY 9647/01 Paper 1 Multiple Choice FRIDAY 16 SEPTEMBER 2011 1 Hour Additional Materials: Multiple Choice Answer Sheet Data Booklet READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. Write and/or shade your name, NRIC / FIN number and HT group on the Multiple Choice Answer Sheet in the spaces provided. There are 40 MCQ questions in 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 Multiple Choice 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. Calculators may be used. This document consists of 18 printed pages. [Turn over]

2 9647/01/CJC JC2 Prelim Exam 2011 Section A For each question there are four possible answers, A, B , C and D . Choose the one you consider to be correct and record your choice in soft pencil on the separate Answer Sheet provided. 1 Use of the Data Booklet is relevant to this question. How many atoms of oxygen are present in 24 cm3 of oxygen gas under room conditions? A 24  6.02  1023 32 B 23106.02 24000242   C 24000 106.022 23 D 1000 106.022 23 2 5.00 g of a fertilizer containing ammonium sulfate was dissolved in water and diluted to 250 cm 3. 25.0 cm3 of this solution was added to an excess of sodium hydroxide solution. The reaction between ammonium sulfate and s odium hydroxide is given by the following equation: (NH4)2SO4 + 2 NaOH → Na2SO4 + 2 H2O + 2 NH3 The ammonia produced was passed into 50.0 cm3 of 0.050 mol dm-3 sulfuric acid solution. The residual acid then required 25.80 cm3 of 0.100 mol dm-3 sodium hydroxide solution for complete neutralisation. What is the percentage by mass of ammonium sulfate (Mr = 132.1) in the fertiliser? A 10.6% B 16.0% C 32.0% D 40.0% 3 A student made up a 0.100 mol dm -3 solution of Ba(OH) 2.8H2O which he found in the laboratory cupboard and left the solution in an open beaker. A week later, he returned to the laboratory, used the solution for titration with 0.100 mol dm -3 HCl and was surprised to discover his titres were lower than expected. Which one of the following reasons explains why the volumes of HC l used were lower than expected? A Some water had evaporated from the barium hydroxide solution. B The concentration of HCl was less than the stated 0.100 mol dm-3. C The barium hydroxide crystals had less water of crystallization than stated. D Some of the barium hydroxide had reacted with c