2022 TSS Chem Prelims P2 SectB

No part of the paper is to be reproduced without the approval of the Principal of Temasek Secondary School Name: Index Number: Class: _______ TEMASEK SECONDARY SCHOOL Preliminary Examination 2022 Secondary 4 Express CHEMISTRY 6092/02 Paper 2 (Section B) 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 three questions from this section. Question B9 is in the form of either/or and only one of the alternatives should be attempted. Write your answers in the spaces provided. 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 of Section A. FOR EXAMINER'S USE Section B /30 This document consists of 10 printed pages.

2 No part of the paper is to be reproduced without the approval of the Principal of Temasek Secondary School. Section B Answer three questions from this section. Question B9 is in the form of either/or and only one of the alternatives should be attempted. Write your answers in the spaces provided. B7 Read the information about the history of the Periodic Table. Chemists spent many years trying to arrange elements in a sensible order. Johann Döbereiner was one of the first chemists to organise elements by their properties. He found out that some sets of three elements seem to fit together because they have similar properties. He called these sets of elements ‘triads’. Table 7.1 shows some elements that could be considered to be triads. Table 7.1 Triad A lithium sodium potassium Triad B calcium strontium barium Triad C chlorine bromine iodine Triad D carbon nitrogen oxygen Döbereiner looked at the relative atomic masses of the elements in some triads. He noticed that the relative atomic mass of the ‘middle’ element was close to the mean (average) relative atomic mass of the first and third element. This was a step forward but did not help with all of the other elements that Döbereiner had not put into groups of three. It was left to others to build on Döbereiner’s work. In 1864, a chemist called John Newlands had an idea of arranging the elements in order, depending on their chemical properties. He called his idea the ‘Law of Octaves’.

3 No part of the paper is to be reproduced without the approval of the Principal of Temasek Secondary School. Table 7.2 shows Newlands’ arrangement of some of the elements. He put elements with similar properties into the same row of his table. Table 7.2