RI 2025+Post+Prelim+TP+QP

© Raffles Institution 2025 9729/02/S/25 [Turn Over RAFFLES INSTITUTION 2025 YEAR 6 TIMED PRACTICE (ADAPTED FROM 2025 TJC Prelim) Higher 2 CANDIDATE NAME CLASS INDEX NUMBER CHEMISTRY 9729/02 Paper 2 Structured Questions 16 October 2025 2 hours Candidates answer on the Question Paper. Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Do not open this question booklet until you are told to do so. Write your name, class and index number in the spaces at the top of this page. 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. Answer all questions in the spaces provided on the Question Paper. The use of an approved scientific calculator is expected, where appropriate. A Data Booklet is provided. Do not write anything in it. You are reminded of the need for good English and clear presentation in your answers. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use 1 / 10 2 / 9 3 / 9 4 / 15 5 / 11 6 / 21 Total / 75 This document consists of 21 printed pages.

© Raffles Institution 2025 9729/02/O/25 [Turn Over 2 Answer all questions in the space provided. 1 (a) In 1932, the American chemist Linus Pauling developed the most common scale of relative electronegativity (EN) values for the elements. The Pauling EN values of elements can be used to predict the chemical properties of compounds. The EN values of four Per iod 3 elements are given in Table 1.1. Table 1.1 element sodium aluminium phosphorus chlorine Pauling EN value 0.93 1.61 2.19 3.16 l (i) Explain the difference in the Pauling electronegativity values of Na and Cl. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..…......... [2] The ionic character of a bond is directly related to the electronegativity difference (∆EN) between the bonded atoms. Fig. 1.1 shows the plot of percent ionic character against ∆EN for NaCl. Fig. 1.1

© Raffles Institution 2025 9729/02/O/25 [Turn Over 3 (ii) Using the values in Table 1.1, calculate ∆EN for AlCl3 and PCl5 respectively. Hence plot the percent ionic character of AlCl3 and PCl5 on Fig. 1.1. Label your points clearly. [2] (iii) Explain the difference in bonding for NaCl and PCl5 in terms of electronegativity. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..….............. ……………………………………………………………………………………..…....