HCI_H2 Chem Prelim P2

1 Candidate Name: _____________________________________ CT Group: 07S______ HWA CHONG INSTITUTION C2 PRELIMINARY EXAMINATION 9746 H2 CHEMISTRY Paper 2 Structured 16 September 2008 1 hour 30 minutes Do not open this booklet until you are told to do so. READ THESE INSTRUCTIONS FIRST Write your name and class clearly in the spaces at the top of this page. Write in dark blue or black pen. You may use a soft pencil for any diagrams, graphs or rough working. Answer all questions in the spaces provided in this question booklet. A Data Booklet is provided. You may use a calculator. The number of marks is given in brackets [ ] at the end of each question or part question. You are reminded of the need for good English and clear presentation in your answers. For Examiner’s Use 1 /11 2 /5 3 /9 4 /15 5 /8 6 /12 Total /60 This question booklet consists of 14 printed pages.

2 Answer all the questions. 1 (a) The table below gives the melting points of some elements of Period 3. Element phorus phos sulphur chlorine Melting point / K 317 392 172 In terms of structure and bonding, explain why sulphur has the highest melting point among the three elements. ...................................................................................................................................................... ...................................................................................................................................................... ...................................................................................................................................................... ...................................................................................................................................................... [2] (b) Sulphur dissolves in aqueous sodium hydroxide to form sodium thiosulphate, Na 2S2O3, and sodium sulphide, Na2S. (i) State the type of reaction taking place. ............................................................................................................................................. (ii) Write ionic half-equations for the reaction and hence construct a balanced equation, including state symbols, for the reaction. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. [3] 9746/02/HCI/C2 Prelim/2008

3 (c) The following test-tube experiments are carried out starting from solid alumin