2025 JC2 Prelims H1 Chem Paper 2 QP_TJC

8873 / TJC Prelims / 2025 DO NOT WRITE IN THIS MARGIN [Turn over TEMASEK JUNIOR COLLEGE 2025 JC2 PRELIMINARY EXAMINATION Higher 1 CANDIDATE NAME CLASS / 24 CENTRE NUMBER S INDEX NUMBER Chemistry 8873/02 Paper 2 Structured Questions 3 September 2025 2 hours Candidates answer on the Question Paper. Additional Materials: Data Booklet READ THESE INSTRUCTIONS FIRST Write your name, CG, centre and index number in the space provided 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. Section A Answer all questions. Section B Answer one question. The use of an approved scientific calculator is expected, where appropriate. The number of marks is given in bracket [ ] at the end of each question or part question. This document consists of 27 printed pages and 1 blank page. For Examiner’s Use Section A Q1 Q2 Q3 Q4 Q5 Section B Q6 /20 Q7 /20 Total /80

2 DO NOT WRITE IN THIS MARGIN 8873 / TJC Prelims / 2025 DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN Section A Answer all the questions in this section in the spaces provided. 1 Steel is an interstitial alloy, as carbon atoms fit in between iron atoms in the lattice. Brass is a substitution alloy, as zinc atoms replace the copper atoms in the lattice. Fig. 1.1 Stainless steel is a combination of interstitial and substitution alloys, because carbon atoms fit in between the lattice, but some of the iron atoms are replaced with nickel atoms. The structure of the alloy will determine properties such as hardness, which measures the material’s resistance to permanent shape change when a force is applied. These properties rely on how much electrostatic attraction is present between ions and electrons in any given volume of the lattice. The magnitude of the lattice strength can be measured using the formula below. Lattice Strength  q r + + (a) The ionic radius and ionic charge of the following ions with their respective chemical symbols are given in the following table. Table 1.1 Element C V Cr Fe Ni Cu Zn W Ionic radius (10-12 m) 15 64 62 55 56 73 74 66 Ionic charge +4 +3 +3 +3 +3 +2 +2 +4 (i) State which metallic element when added in small amount increase s the lattice strength of iron to the largest extent. Give a reason for your answer. ………………………………………………………………………………………………….. ………………………………………………………………………………………………..[1] (ii) From the Table 1.1 above, suggest another element, other than nickel, that can be added to iron to form a substitutional alloy. ………………………………………………………………………………………………..[1]

3 DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN DO NOT WRITE IN THIS MARGIN 8873 / TJC Prelims / 2025 DO NOT WRITE