2019 ACJC Prelim H2 Chem P2 QP

1 © ACJC2019 9729/02/Prelim Exam/2019 [Turn over Index No. Name Form Class Tutorial Class Subject Tutor ANGLO-CHINESE JUNIOR COLLEGE DEPARTMENT OF CHEMISTRY Preliminary Examination CHEMISTRY 9729/02 Higher 2 Paper 2 Structured Questions 26 August 2019 2 hours Candidates answer on the Question Paper. Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Write your name, index number, form class, tutorial class and subject tutor’s name on all the work you hand in. Write in dark blue or black pen. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, glue or correction fluid. Answer all questions in the spaces provided on the Question Paper. The use of an approved scientific calculator is expected, where appropriate. A Data Booklet is provided. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner's Use Question no. Marks 1 / 7 2 / 21 3 / 15 4 / 7 5 / 11 6 / 14 TOTAL / 75 This document consists of 22 printed pages. 9729/02/Prelim/19 ANGLO-CHINESE JUNIOR COLLEGE © ACJC 2019 Department of Chemistry [Turn over

2 © ACJC2019 9729/02/Prelim Exam/2019 [Turn over 1 (a) The element aluminium and its compounds have some properties characteristic of metals, and some of non -metals. Aluminium hydroxide, for example, is known to be amphoteric. (i) Explain the meaning of the word “amphoteric”. [1] …………………………………………………………………………………… ……………………………………………………………………………………. ……………………………………………………………………………………. Aluminium sulfate and calcium oxide are sometimes added to water supplies to co - precipitate suspended solids and bacteria. A small amount of aluminium -containing ions remains in solution and its presence in drinking water may contribute to the mental illness known as Alzheimer’s disease. (ii) Write a balanced equation for the reaction that occurs when aluminium sulfate and calcium oxide are added to water, given that aluminium hydroxide is one of the products formed. [1] …………………………………………………………………………… (iii) By considering the nature of calcium oxide, explain why adding too much of it would increase the risk of contracting Alzheimer’s disease. Write an equation to illustrate how “aluminium-containing ions remains in (drinking water)” as a result of adding too much calcium oxide. [2] ………………………………………………………………………