Copy of CHS 2024_S4_OP_Prelim Paper 2 Section B

[Turn Over Name: Index Number: Class: CATHOLIC HIGH SCHOOL Preliminary Examination Secondary 4 ‘O’ Level Programme CHEMISTRY 6092/02 Paper 2 20 August 2024 1 hour 45 minutes Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your name, index number and class on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Section B Answer one question. Write your answers in the spaces provided. 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 6. The use of an approved scientific calculator is expected, where appropriate. For examiner’s use only: Section B / 10 This document consists of 6 printed pages. B

2 Section B Answer one question from this section. 10 Malonic acid is a white crystalline solid which is soluble in water. Fig. 10.1 shows the structural formula of malonic acid. CH2(COOH)2 or HOOC–CH2–COOH Fig. 10.1 Malonic acid ionises according to the equation below. CH2(COOH)2 ⇌ 2H+ + CH2(COO)22− (a) State one similarity between the acidic behaviour of malonic acid and sulfuric acid. ……………………………………………………………………………………………………... …………………………………………………………………………………………….….… [1] (b) Experiments are carried out using equal volumes of malonic acid and sulfuric acid of the same concentration to investigate their properties. Compare and explain the properties of malonic acid and sulfuric acid. Your answer should include a discussion of the similarities and differences in their • pH • reaction with excess solid sodium carbonate. …………………………………………………………………………….……………………….. ………………………………………………………………………….………………………….. ………………………………………………………………………….………………………….. …………………………………………………………………………………….……………….. …………………………………………………………………………………….……………….. …………………………………………………………………………………….……………….. …………………………………………………………………………………….……………….. …………………………………………………………………………………….……………….. …………………………………………………………………………………….……………. [5]

3 [Turn Over (c) Compound A, C3H8O2, reacts with acidified potassium manganate( VII) to form malonic acid. (i) Name the type of reaction compound A undergoes to form malonic acid. ………………………………………………………………………………………..... [1] (ii) Draw the displayed formula of compound A. [1] (iii) Name the homologous series that contains the functional group in compound A. ………………………………………………………………………………………..... [1] (iv) Using a different reagent, compound A forms compound B. The structure of compound B is shown in Fig. 10.2. H–C–CH2–C–H Fig. 10.2 Are malonic acid and compound B isomers? Explain yo