2022 JVSS Chem Prelims P1

This document consists of 15 printed pages. [Turn over JURONGVILLE SECONDARY SCHOOL PRELIMINARY EXAMINATION 2022 Secondary 4 Express STUDENT NAME CLASS INDEX NUMBER CHEMISTRY 6092/01 Paper 1 Multiple Choice 26 August 2022 1 hour Additional Materials: Multiple Choice Answer Sheet READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. Write your name, class and index number in the spaces on all the work you hand in. There are forty questions on this paper. Answe r 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 Multiple Choice Answer Sheet. Read the instructions on the Answer Sheet very carefully. 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. A copy of the Periodic Table is printed on page 15. The use of an approved scientific calculator is expected, where appropriate. DO NOT OPEN THE BOOKLET UNTIL YOU ARE TOLD TO DO SO Setter: Mrs Wong Yan Pure ���

2 1 Four identical gas jars are filled with different gases. The lids are taken off the gas jars and they are left open to the air for a few hours. Which gas jar will first contain the most air in it? A B C D 2 A pale green solution X gives a green precipitate with excess aqueous sodium hydroxide. An alkaline gas is only given off when the mixture is warmed with powdered aluminium. Which ions does X contain? A ammonium and copper(II) ions B ammonium and iron(II) ions C copper(II) and nitrate ions D iron(II) and nitrate ions 3 Which app aratus cannot be used to measure the rate of neutralis ation between sol id sodium carbonate and aqueous hydrochloric acid? A electronic balance B gas syringe C stopwatch D thermometer Cl2 CO NH3 SO2 ���

3 4 An analysis is carried out on a plant extract containing some coloured pigments. In Fig. 4.1, a small amount of plant extract is dotted on a chromato graphy paper and separated using solvent A. After drying the chromatography paper, the chromatography paper is subjected to another separation using solvent B, as shown in Fig. 4.2. Fig. 4.1 Fig. 4.2 Which statement is not true? A Pigment 2 is less soluble in solvent A than in solvent B. B Pigment 4 is most likely a pure substance. C Pigments 1 and 3 have a same substance. D The components in pigment 1 have different solubilities in solvent B. 5 An ion X+ contains 23 nucleons and 10 electrons. What does the nucleus of the ion X+ contain? protons neutrons A 9 14 B 10 13 C 11 11 D 11 12 [Turn over rotate 90 o anticlockwise 4 3 2 1 first starting line plant extract first starting line second starting line ���

4 6 A covalent compound has the following structural formula. X – Y ≡ Z Which row shows the possible electronic structures of the atoms X, Y and Z? X Y Z A 1 2,2 2,5 B 1 2,4 2,3 C 2,8,7 2,2 2,3 D 2,8,7 2,4 2,5 7 Peeling onions often cause tearing of the eyes due to the release of a sulfide compound. Peeling them under running water reduces the problem. Which statements are true of the sulfide compound? 1 It has a low boiling point. 2 It has small and light ions with weak bonding. 3 It is a covalent compound with weak covalent bonds. 4 It is soluble in water. A 1 and 2 only B 1 and 4 only C 2 and 3 only D 3 and 4 only 8 The strongest ionic crystal lattices are generally observed to consist of highly charged ions combined in a 1 : 1 ratio. Which two elements are likely to form crystals with the highest melting point? A aluminium and oxygen B calcium and fluorine C lithium and fluorine D magnesium and oxygen 9 Sulfur vapour with a mass of 128 g has the same volume as 16 g of oxygen at th e same temperature and pressure. What is the formula of a molecule of sulfur vapour? A S2 B S4 C S6 D S8 ���

5 10 75 cm 3 of 0.200 mol / dm3 of sodium h ydroxide is added to 25 cm 3 of 0.200 mol / dm 3 sulfuric acid. What is the concentration of the excess sodium hydroxide in the resultant solution? A 0.005 mol / dm3 B 0.010 mol / dm3 C 0.030 mol / dm3 D 0.050 mol / dm3 11 A student carried out an electrolytic purification of copper as shown. The table shows the information about this electrolytic purification. mass of before electrolytic purification / g after electrolytic purification / g anode 100 10 cathode 10 80 What was the percentage impurity of the impure copper anode? A 10.0 % B 20.0 % C 30.0 % D 90.0 % 12 When gold plating an orchid, a coating containing fine metal or carbon particles i s first painted onto the orchid. Why is this coating applied? A It allows the gold to form a tough alloy on the orchid’s surface. B It gives the orchid a conductive surface so that it can act as the anode. C It gives the orchid a conductive surface so that it can act as the cathode. D It gives the orchid a sticky surface so that the gold plating will not fall off. [Turn over impure copper pure copper aqueous copper(II) sulfate ���

6 13 Which observation will be made when dilute sulf uric acid is electrolysed using graphite electrodes? A No gas is evolved at both the cathode and anode. B The gas evolved at the anode extinguishes a lighted splint with a ‘pop’ sound. C The gas evolved at the cathode is less dense than air. D The gas evolved at the cathode relights a glowing splint. 14 The figure shows the set-up of a simple cell involving iron and copper electrodes immersed in their respective electrolytes. Which statement is not true for the experiment? A The colour intensity of copper(II) solution decreases over time. B The electrons flow from left to right through the salt bridge. C There is a decrease in the mass of iron electrode. D There is an increase in the mass of copper electrode. 15 The table shows the e nergy released by the complete combustion of some compounds used as fuels. compound formula Mr ΔH / kJ / mol methane CH4 16 –880 ethanol C2H5OH 46 –1380 propane C3H8 44 –220 heptane C7H16 100 –4800 Which fuel produces the most energy when 1 g of the compound is completely burnt? A methane B ethanol C propane D heptane copper electrode voltmeter iron electrode Cu2+ (aq) Fe2+ (aq) salt bridge ���

7 16 The equations for three reactions are given. reaction 1 H2  2H reaction 2 2H + O  H2O reaction 3 HCl  H + Cl Which of these reactions are endothermic? A reaction 1 only B reactions 1 and 2 only C reactions 1 and 3 only D reactions 2 and 3 only 17 The energy profile diagram for the following reaction is shown. M + N P ΔH = –108 kJ / mol Which equation represents the activation energy of the forward reaction? A E1 + E2 B E2 – E1 C E3 – E1 D E3 – E2 [Turn over energy / kJ progress of reaction E1 E2 E3 M + N P ���

8 18 Curve I is obtai ned by the decomposition of 50 cm 3 of 1 mol / dm3 aqueous hydrogen peroxide, catalysed by manganese(IV) oxide. 2H2O2(aq)  O2(g) + 2H2O(l) Which change will produce curve II? A adding 60 cm3 of 1 mol / dm3 aqueous hydrogen peroxide B adding 100 cm3 of 0.1 mol / dm3 aqueous hydrogen peroxide C lowering the temperature D using 75 cm3 of 0.5 mol / dm3 aqueous hydrogen peroxide instead 19 Which observation is that of a redox reaction? A Aqueous potassium iodide turns brown when chlorine gas is bubbled into it. B Blue precipitate is formed when aqu