2021 Sec 3 Science Chemistry EOY Chua Chu Kang Secondary with Answer

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BP-642022 Sec 3 Science Chemistry SA2 Chua Chu Kang Sec 1 Gas X is collected using the apparatus set-up shown below. gas X -) Based on this set-up, what can be infened about gas X? It is denser than air. It is less dense than air. It is insoluble in water. It is soluble in water. A pipette B gas syringe C measuring cylinder D burette Which of the following separation methods is suitable for obtaining zinc nitrate from aqueous zinc nitrate solution? A crystallisation B distillation C evaporation O filtration PartnerlnLearning A B c D 2 Which instrument can most accurately measure 24.5 cm3 of aqueous sodium hydroxide? 3 b5

BP-65 2 4 The table shows information about the solubilities of three solids. solid solubility in water solubility in ethanol P o R insoluble soluble insoluble insoluble insoluble soluble Some or all of the following steps must be taken to obtain pure R from a mixture of P, Q and R. 1. filter 2. evaporate filtrate till dryness 3. add ethanol 4. add water ln what order should the required steps be taken to obtain pure R from a mixture of P, Q and R? A 3, 1,2 B 4, 1,2 c 3,4, 1,2 o 4,3, 1,2 The particles in substance Z are widely spaced and able to move freely. Z changes to a state in which the particles are closely packed but still able to move freely. What is this change called? A melting B freezing C evaporation D condensation PartnerlnLearning 64 5

BP-66 3 6 The melting point of a compound, acetone is -95'C and its boiling point is 56"C. The diagrams show the arangement of particles in acetone at two different temperatures: X'C and Y'C. o ooco a) ooo r.) x"c Y'C What could be the values of X and Y? 7 Which of the following is not a mixture? air bronze liquid nitrogen sea water PartnerlnLeaming 65 A B c D n o L-) (, {t o x A B c D 50 50 60 60 -100 -90 -100 -90

BP-67 4 8 The diagrams below show the observations of the appearance of powdered iron and sulphur placed in a test tube before and after heating. after suong heating @yellowish powder and greyish powder dull powder diagram 1 Which of the following description is conect? diagram 2 9 Four elements have the following electronic configurations. 2, 1 X 2,4 2,5 z 2,8 Which statement is conect? A All four elements are in the same group in the Periodic Table. B All four elements are in Period 3 of the Periodic Table. C Element W is a metal but X, Y and z are non-metals. D Element Z is a metal but W, X and Y are non-metals. PartnerlnLearning 66 diagram 1 diagram 2 A B c D a mixture of compounds a mixture of elements a mixture of compounds a mixture of elements a compound a compound a mixture of elements a mixture of elements

BP-68 5 1O Which of the following pairs contains particles which have equal and opposite charges? A a proton and a hydrogen ion B a neutron and an electron C a neutron and a hydrogen nucleus D a proton and an electron 11 atomic number nucleon number A B c D 8 12 21 22 16 24 45 48 12 Which property best indicates that a substance is an ionic compound? A lt is a crystalline solid at room temperature. B lt is insoluble in water. C lt can be synthesised from its element. D lt conducts electricity in molten state. 13 The ion of metal X is represented by the symbol X3*. What will the formula of its chlodde be? A XCls B )QC/3. c &c/ D &C/, PartnerlnLeaming 67 Which element in the table has atoms containing 24 neutrons each?

BP-69 6 14 The table shows the number of particles present in the nuclei of four atoms or ions. protons neutrons electronic structure 1 2 3 4 18 19 '19 20 22 20 21 20 2,8,8 2,8,8 2,8,8,1 2,8,8,2 Which two particles belong to the same element? 1and2 1and4 2and3 2and4 't5 NHa Oz Nz COz 16 The oxide of an element X is added separately to hydrochloric acid and aqueous sodium hydroxide. The word equations for the reactions are shom. X oide + hydrochloric acid + X chloride + water X oide + sodium hydroxide -.> no reaction Which row describes element X and its oxide? x X oxide A B c D metal metal non-metal non-metal acidic basic basic acidic PartnerlnLeaming 68 A B c D A B c D Which molecule contains single covalent bonds only?

BP-70 7 17 Which compound can be used to reduce excess acidity in soil? calcium chloride calcium nitrate calcium oxide calcium sulfate 18 Bubbles of gas were observed when a piece of sodium carbonate was added to hydrochloric acid. Which of the following correctly identifies the gas produced? A carbon dioxide B hydrogen C ammonia D orygen 19 Which ions are present in chromium sutfate, Crz(SOa)3? A Cf* and SOr2- B Crs. and SOr2- C Cl- and SOa! D Cr3. and SOr$ 20 argon helium krypton neon END OF PAPER 1 PartnerlnLeaming 69 A B c D Which gas has the highest percentage composition in dry air? A B c D

BP-72 ,| Section A Answer all the questions in the spaces provided. A student is measuring the volume of gas produced when a strip of magnesium ribbon is reacted with dilute hydrochloric acid using the set-up given in Fig 1.1. Apparatus W is attached to the side-arm of the test tube. side-arm test tube bung excess dilute hydrochloric acid magnesium ribbon Fig 1.1 (a) Name apparatus W. (b) During the reaction, he observed that the sides of the test{ube felt warm. He decided that he should carry out the experiment again to determine the temperature change that occurs. State the apparatus that he would need to include in the set-up. t11 [otal: 2] PartnerlnLearning 71 apparatus W o o o o t1I

BP-73 2 2 A student separates a mixure of pentane (boiling point: 36 "C) and hexane (boiling point: 68 oC) using the set-up shown in Fig. 2.1. therm water in I A water out conical flask mixture of pgntane and hexane heat Ftg.2.1 (a) (D State the general name for this method of separation. t1l (ii) Name apparatus A. (iii) State the purpose of apparatus B. B tt t1l (b) ldentify two enors in the student's set-up. I 2. 12) ['otal: 5] Partnerl nLeamingqi6PH@ YAfi 7? tll