2022 NTSS Chemistry P3

1 This document consists of 18 printed pages. Setter: Ms Caley Ng NEW TOWN SECONDARY SCHOOL Preliminary Examination Secondary 4 Express / 5 Normal (Academic) NAME CLASS INDEX NUMBER Science (Chemistry) Paper 3 Chemistry Candidates answer on the Question Paper. No Additional Materials are required. 5076/03, 5078/03 19 August 2022 1 hour 15 minutes 1100 – 1215 READ THESE INSTRUCTIONS FIRST Write your name, register number and class in the spaces provided above. You may use an HB pencil for any diagrams, graphs, tables or rough working. Write in dark blue or black pen. Do not use staples, paper clips, glue or correction fluid. The use of an approved scientific calculator is expected, where appropriate. You may lose marks if you do not show your working or if you do not use appropriate units. Section A (45 marks) Answer all questions. Write your answers in the spaces provided on the question paper. For Examiner’s Use Paper 1 Paper 3 Section A Paper 3 Section B Q___ Q___ Total Section B (20 marks) Answer any two questions. Write your answers in the spaces provided on the question Paper. A copy of the Data Sheet is printed on page 17. A copy of the Periodic Table is printed on page 18. The number of marks is given in brackets [ ] at the end of each question or part question.

2 Section A (45 marks) Answer all the questions in the spaces provided. 1 Choose from the following substances to answer the questions. nitrogen dioxide argon calcium hydroxide carbon monoxide oxygen lithium oxide sodium hydroxide zinc oxide Each substance may be used once, more than once or not at all. Identify the substance which (a) contributes to acid rain ……………………………………………………………………………………… [1] (b) is used to control pH in soils ……………………………………………………………………………………… [1] (c) reacts with both acids and bases ……………………………………………………………………………………… [1] (d) is used to fill tungsten bulbs ……………………………………………………………………………………… [1] [Total: 4]

3 2 24Mg, 25Mg and 26Mg are isotopes of magnesium. (a) Define isotopes. ……………………………………………………………………………………………. ………………………………………………………………………………………… [1] (b) Complete Table 2.1 to describe the structure of a magnesium atom and a magnesium ion. Table 2.1 number of protons neutrons electrons a 24Mg atom 12 a 25Mg ion 10 [4] (c) A student made the following claim: “The chemical formula for magnesium chloride is MgCl2, no matter which isotope is used.” With reference to the electronic configuration of magnesium, explain if you agree with the student. ……………………………………………………………………………………………. ……………………………………………………………………………………………. ……………………………………………………………………………………………. …………………………………………………………………………………….…... [2] [Total: 7]

4 3 In the early 1800’s, Friedrich Wöhler, a German chemist, first isolated beryllium metal. The chemical equation for the reaction he used to isolate beryllium metal from beryllium chloride is: BeCl2 (s) + 2K (s) → 2KCl (s)