YTSS Sc(Chem) Prelim P3 QP

NAME: ( ) CLASS: YISHUN TOWN SECONDARY SCHOOL PRELIMINARY EXAMINATION 2025 SECONDARY 4 & 5 G3 SCIENCE (CHEMISTRY) (5086/3) DATE : 15 Aug 2025 DAY : Friday DURATION: 1 hr 15 min MARKS: 65 marks READ THIS INSTRUCTIONS FIRST Write your name, class and register number in the spaces provided at the top of this page. Section A Answer all the questions. Write your answers in the spaces provided. Section B Answer one question. Write your answers in the spaces provided. INFORMATION FOR CANDIDATES The number of marks is given in brackets [ ] at the end of each question or part question. You may use an approved calculator. A copy of the Periodic Table and Colours of Metal Hydroxides are printed on the last two pages. Section A Section B TOTAL This paper consists of 17 printed pages.

2 Section A Answer all the questions. 1 Choose from the following substances to answer the questions. PbSO4 Al2O3 CaSO4 Al(NO3)3 CuCO3 KOH ZnCl2 (NH4)2SO4 Each substance may be used once, more than once, or not at all. Which substance (a) gives a white precipitate that dissolves in excess aqueous ammonia. ….…………. [1] (b) reacts with both acid and alkali. ….…………. [1] (c) reacts with an acid to produce a salt, a gas and water. ….…………. [1] (d) gives out a gas that turns damp red litmus paper blue when warmed with sodium hydroxide. ….…………. [1] [4] 2 The apparatus shown in Fig. 2.1 can be used to separate hexane (boiling point 70°C) and heptane (boiling point 98°C). Fig. 2.1

3 (a) Describe the role of apparatus A. ………………………………………………………………………………………... ………………………………………………………………………………………... [1] (b) Identify the distillate first collected. ………………………………………………………………………………………... [1] (c) Describe the changes in the arrangement and movement of particles in hexane when it is heated from 25 ºC to 80 ºC. arrangement : ………………………………………………………………………………………... ………………………………………………………………………………………... movement : ………………………………………………………………………………………... .……………………………………………………………………………………….. [2] 3 The atomic radius is a measure of the size of an atom. The ionic radius is a measure of the size of an ion. The table below shows the information on the atomic and ionic radii of Period 3 elements. Silicon is excluded as it does not form ions.

4 (a) Complete the table to show the electronic structure of each ion. [2] (b) (i) State one difference between the atomic radii of metals and non- metals. ………………………………………………………………………………… ………………………………………………………………………………… [1] (ii) State one difference between the ionic radii of metal io