2025 YTSS Prelim 4E5N G3 Sc(Chem) P1

NAME: ( ) CLASS: YISHUN TOWN SECONDARY SCHOOL PRELIMINARY EXAMINATION 2025 SECONDARY 4 & 5 G3 SCIENCE (CHEMISTRY) (5086/1) DATE : 14 Aug 2025 DAY : Thursday DURATION : 1 hr MARKS : 20 marks ADDITIONAL MATERIALS Multiple Choice Answer Sheet (OMS) READ THESE INSTRUCTIONS FIRST Write your name, class and register number in the spaces provided at the top of this page. There are twenty questions. Answer all questions. For each question, there are four possible answers, A, B, C and D. Choose the one you consider correct and record your choice in soft pencil on the separate answer sheet. Read very carefully the instructions on the answer sheet. INFORMATION FOR CANDIDATES Each correct answer will score one mark. A mark will not be deducted for a wrong answer. Any rough working should be done in this booklet. You may use an approved calculator. A copy of the Periodic Table and Colours of Metal Hydroxides are printed on the last two pages. This paper consists of 10 printed pages.

2 Multiple Choice Questions (20 marks) 1 Two methods of gas collection are shown below. Which row correctly describes the properties of a gas which allow it to be collected by both methods? solubility in water density A insoluble in water denser than air B insoluble in water less dense than air C soluble in water denser than air D soluble in water less dense than air 2 Food dyes, 1 and 2 are known to contain one or more of the three substances X, Y and Z. Two chromatograms are developed; one used water as the solvent, and the other used ethanol. The results are shown in the diagram below. Which statements are correct? I Substance Y is likely to be pure. II The component in Z is less soluble in water than in ethanol. III There is a component in sample 1 that is insoluble in water but soluble in ethanol. A I and II only B I and III only C II and III only D All of the above gas jar gas measuring cylinder water gas method I method II

3 3 The graph below shows how temperature changes over time when liquid S was cooled. Which statement incorrectly describes the cooling curve of liquid S? A Heat energy is gained by the particles at region XY to overcome the forces of attraction. B There is a mixture of solid and liquid at region XY. C The particles are vibrating about fixed positions at region YZ. D The particles are arranged closely in a disorderly manner at region WX. 4 Element G has an electronic structure of 2,8,1. Which statements about element G are correct? I II G reacts with cold water. G forms an ion of -1 charge. III G is in Period 3 of the Periodic Table. A I and II only B I and III only C II and III only D All of the above 5 There are a few isotopes for uranium atom. One such atom is uranium-235. What is a possible atomic structure of another isotope of uranium-235? number of protons number of neutrons number of electrons A 90 143 92 B 92 143 90 C 90 146 90 D 92 146 92 temperature / °C W X Y Z time / min 60 50 40 30 20 10 0

4 6 Four set-ups are shown below. Key 1 2 3 4 In which set-ups will the bulb light up? A 1 and 2 only B 2 and 4 only C 1, 2 and 4 only D All of the above 7 The statements below contain descriptions of four different substances Q, R, S and T. substance description Q A reddish liquid that boils at 59 oC and cannot be broken down into simpler substances. R White solid that melts over a range of temperatures. S A white solid that partially dissolves when placed in a beaker of excess water. It can be separated into a colourless solution and white residue by filtration. T A purple substance that has a constant composition and decomposes into two elements when heated. What is the correct classification of the four substances? element compound mixture A Q T R and S B Q R and T S C S R and T Q D Q and R S T - bulb - batteries aqueous magnesium chloride molten magnesium chloride solid magnesium chloride magnesium ribbon

5 8 Which observation is correct? reaction between observation A aqueous copper(II) sulfate and barium nitrate blue precipitate and colourless solution obtained B aqueous sodium chloride and silver nitrate white precipitate and green solution obtained C calcium carbonate and hydrochloric acid effervescence observed colourless gas extinguished a lighted splint with a ‘pop’ sound D sodium hydroxide and ammonium carbonate colourless gas turned moist red litmus paper blue on warming 9 Which substance has the least number of moles? A 6 g of hydrogen molecules B 48 g of magnesium atoms C 100 cm3 of 0.25 mol/dm3 aqueous sodium chloride D 24 000 cm3 of ammonia gas at room temperature and pressure 10 Magnesium reacts with hydrochloric acid. Mg (s) + 2HCl (aq) → MgCl2 (aq) + H2 (g) What is the volume of hydrogen gas produced at room temperature and pressure if 6.0 g of magnesium reacts with 100 cm3 of 0.10 mol/dm3 hydrochloric acid? A 0.06 dm3 B 0.12 dm3 C 3.00 dm3 D 6.00 dm3 11 The table below shows the reaction of four metals, W, X, Y and Z, with water and steam. metal reaction with water reaction with steam W catches fire explodes X no change no change Y no change slow effervescence Z slow effervescence rapid effervescence What is the order of reactivity of the metals from most reactive to least reactive? A X → Y → Z → W B W → Y → Z → X C X → Z → Y → W D W → Z → Y → X

6 12 A student carried out two experiments by mixing marble and dilute hydrochloric acid together. Experiment 1 Excess finely powdered marble and 20 cm3 of 0.10 mol/dm3 dilute hydrochloric acid Experiment 2 Excess marble chips and 20 cm3 of 0.10 mol/dm3 dilute hydrochloric acid The total volume of carbon dioxide given off is determined at regular time intervals and plotted in the following graph. Which curves are obtained in the two experiments? experiment 1 experiment 2 A X Z B X Y C Y Z D Y X 13 In which reaction is hydrochloric acid not behaving as an acid? A HCl + AgNO3 → AgCl + HNO3 B 2HCl + CaCO3 → CaCl2+ H2O + CO2 C 2HCl + Fe → FeCl2 + H2 D 6HCl + Fe2O3 → 2FeCl3 + 3H2O total volume of CO2/ cm3

7 14 What are the oxidation states of chlorine in Cl2O and ClO4- ? Cl2O ClO4- A -2 -1 B +1 +3 C +1 +7 D +2 +8 15 Solid barium hydroxide is added into a beaker containing crystalline ammonium chloride and the mixture is stirred. When the two solids re act, a thin layer of ice forms on the external surface of the beaker. Which graph shows how the temperature of the mixture changes as the reaction progresses and the remaining mixture is left to stand for some time? 16 The apparatus shown below was set up by a student to investigate the effect of air on rusting. The student discovered that after a few days, the height of the water in the test tube rose by 4 cm. What was the original volume of air found in the test tube? A 4 cm3 B 10 cm3 C 20 cm3 D 40 cm3

8 17 Which pollutant, from the combustion of petrol in an internal combustion engine, can cause limestone buildings to corrode? A carbon B carbon monoxide C nitrogen dioxide D unburnt hydrocarbon 18 Which statement about alkenes is incorrect? A They