2022 TSS Chem Prelims P2 SectA

Name: Index Number: Class: _______ TEMASEK SECONDARY SCHOOL Preliminary Examination 2022 Secondary 4 Express CHEMISTRY 6092/02 Paper 2 (Section A) Total duration for Sections A and B: 1 hour 45 minutes Question and Answer Booklet READ THESE INSTRUCTIONS FIRST Do not open the booklet until you are told to do so. Hand in this booklet at the end of the paper. Write your name, index number and class in all the work you hand in. Write in dark blue or black pen. Answer all questions in the spaces provided on the question paper. At the end of the examination, submit Section A and B separately. The number of marks is given in brackets [ ] at the end of each question or part question. A copy of the Periodic Table is printed on page 14. FOR EXAMINER'S USE Section A /50 This document consists of 14 printed page.

2 No part of the paper is to be reproduced without the approval of the Principal of Temasek Secondary School. Section A Answer all the questions in this section in the spaces provided. The total mark for this section is 50. A1 All nitrates of Group II metal undergo thermal decomposition to form metal oxide, nitrogen dioxide and oxygen. (a) Describe a test to confirm that decomposition has taken place. ……………………………………………………………………………………… ……………………………………………………………………………………… ………………………………………...………………………………………….[2] (b) Table 1.1 shows the temperature at which each metal nitrate salt decomposes. Table 1.1 metal nitrate salt Temperature at which metal nitrate salt decomposes/ °C magnesium nitrate 330 calcium nitrate 500 strontium nitrate 570 barium nitrate 650 (i) Using Table 1.1, deduce the order of reactivity of the four metals. most reactive ……………………………………. ……………………………………. ……………………………………. least reactive ……………………………………. [1] (ii) Explain your answer in (b)(i). ………………………………………………………………………..……... ……………………………………………………………………..………... .…………………………………………………………………..…….....[2]

3 No part of the paper is to be reproduced without the approval of the Principal of Temasek Secondary School. A2 Fig. 2.1 shows a mixture of the gases, methane, ammonia and water vapour in a flask. The electrodes provide electric sparks which causes chemical reactions to occur. Fig. 2.1 (a) The substances present at the start of the experiment are compounds consisting of small molecules. Explain what is meant by molecule. ……………………………………………………………………………………… ………………………………………...………………………………………….[1] (b) After one week , the experiment produced a mixture of products. The mixture of products can be analysed using paper chromatography. Four known compounds, glycine, alanine, cysteine