SST Class Test 2 Chem

Page 1 of 11 [Turn over [ Turn over 2023 SECONDARY 3 CLASS TEST 2 CHEMISTRY 18 August 2023 (Friday) 50 minutes CANDIDATE NAME CLASS INDEX NUMBER READ THESE INSTRUCTIONS FIRST Do not turn over the page until you are told to do so. Write your name, class, and index number in the spaces provided above. Write in dark blue or black pen. Do not use staples, paper clips, highlighters, glue or correction fluid/tape. Section A There are ten questions in this section. 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 the table on Page 2. Sections B Answer all the questions. Write your answers in the spaces provided on the question paper. INFORMATION FOR CANDIDATES The number of marks is given in brackets [ ] at the end of each question or part question. The total mark for this paper is 40. Approved electronic calculators are allowed for use in this paper. A copy of the Periodic Table is printed on page 11. This document consists of 11 printed pages including the cover page. Section A Section B Total 40 For Examiner’s Use

Page 2 of 11 [Turn over [ Turn over Section A Write your answers clearly in the table below. Question 1 2 3 4 5 6 7 8 9 10 Answer 1 Element P has a lattice of positive ions and a ‘sea of electrons’. Which statement describes P? A It conducts electricity by the movement of ions and electrons. B It is not malleable. C It is decomposed by an electric current. D It requires a large amount of heat to change its state from solid to liquid. 2 Nitrogen crystals are obtained by freezing nitrogen at -196 oC. What will the nitrogen crystals contain? A nitrogen atoms only B nitrogen molecules only C nitrogen atoms and molecules D nitrogen ions and nitrogen atoms 3 Which diagram shows the structure of graphite?

Page 3 of 11 [Turn over [ Turn over 4 Sulfur forms compounds with the elements hydrogen, oxygen and magnesium. These compounds have the formulae X2S, YS and SZ2, where S represents sulfur. What are the identities of X, Y and Z? H O Mg A Z X Y B Y X Z C X Z Y D Z Y X 5 The Avogadro constant is the number of A atoms in 24 g of magnesium. B atoms in 28 g of helium. C chloride ions in 95 g of magnesium chloride. D molecules in 35.5 g of chlorine. 6 Silver ions react with chloride ions as shown in the ionic equation below. Ag+(aq) + Cl- (aq) ⟶ AgCl(s) It is found that 5 cm3 of a 0.1 mol/dm3 solution of the chloride of metal Q needs 10 cm3 of 0.1 mol/dm3 silver nitrate for complete reaction. What is the formula of the chloride of metal Q? A QCl4 B Q2Cl C QCl D QCl2 7 On adding 50 g of impure limestone, CaCO3 (Mr = 100), to excess hydrochloric acid, 6.0 dm3 of CO2 was evolved at room temperature and pressure. What is the purity of the limestone? A 25% B 50% C 75% D 100% 8 Which one of the following is the ionic equation for the reaction between magnesium and hydrochloric acid? A Mg (s) + 2H+ (aq)⟶ Mg2+ (aq) + H2 (g) B Mg (s) + H+ (aq)⟶ Mg+ (aq) + H (g) C Mg2+ (s) + 2H+ (aq)⟶ Mg2+ (aq) + 2H (g) D Mg (s) + 2H (aq)⟶ Mg(aq) + 2H (g)

Page 4 of 11 [Turn over [ Turn over 9 The colour of an indicator in solutions of different pH is shown below. pH 0 2 4 6 8 10 12 14 colour red orange yellow Which two solutions can be distinguished using the indicator? A aqueous ammonia and aqueous sodium hydroxide B aqueous hydrogen chloride and aqueous carbon dioxide gas C aqueous sodium hydroxide and aqueous sodium chloride D aqueous sodium chloride and water 10 Waste water from a factory was found to have a pH of 2. Which substance could be used to neutralise the waste water before it is released into a river? A calcium hydroxide B calcium sulfate C sodium chloride D sulfur dioxide

Page 5 of 11 [Turn over [ Turn over Section B Answer all questions. Write your answers in the spaces provided. 1 Name an element from Period 3, sodium to argon, that matches the description for each of the following. You may use each element once, more than once, or not at all. (a) It forms an insoluble basic oxide. …………………………………… (b) It forms a substance that has a giant molecular structure with oxygen. …………………………………… (c) It reacts with oxygen to form a gas that turns damp blue litmus paper red. …………………………………… (d) It forms an ion by gaining three electrons. …………………………………… (e) It forms a covalent compound with nitrogen. The ratio of the number of atoms of the element and nitrogen is 3:1 in the covalent compound. …………………………………… [Total: 5 marks] 2 Chlorofluorocarbons (C FCs) are compounds that contain only carbon, chlorine and fluorine. They are atmospheric pollutants and destroy ozone in the upper atmosphere. (a) ‘CFC11’ has the following composition by mass: C : 8.7% , F : 13.8% , Cl : 77.5% Calculate and state the empirical formula of ‘CFC11’. [3]

Page 6 of 11 [Turn over [ Turn over (b) ‘CFC12’ has the molecular formula CF 2Cl2. ‘CFC12’ can be made by the reaction of hydrogen fluoride, HF, with tetrachloromethane, CC l4, forming hydrogen chloride as a by-product. (i) Draw the ‘dot-and-cross’ diagram of ‘CFC12’. Show valence electrons only.[2] (ii) Write a balanced chemical equation to show the formation of ‘CFC12’. [1] ..……..……………………………………………………………………………….......... (iii) 10.0 g of hydrogen fluoride and 36.0 dm3 of tetrachloromethane gas were reacted to produce ‘CFC12’. Determine the limiting reagent for this reaction. Hence, calculate the maximum mass of ‘CFC12’ that can be produced. [4] [Total:10 marks]

Page 7 of 11 [Turn over [ Turn over 3 Potassium sulfate can be prepared from the reaction between aqueous potassium hydroxide and dilute sulfuric acid. (a) Describe how a solution of potassium sulfate can be prepared using the reagents provided. [4] ……………………………………………………………………………………………..……… ………………………………………………………………………………………………..…… ……………………………………………………………………………………………..……… ………………………………………………………………………………………………..…… ……………………………………………………………………………………………..……… ………………………………………………………………………………………………..…… ……………………………………………………………………………………………..……… ……………………………………………………………………………………………..……… ………………………………………………………………………………………………..…… ……………………………………………………………………………………………..……… ………………………………………………………………………………………………..…… ……………………………………………………………………………………………..……… ……………………………………………………………………………………………..……… ………………………………………………………………………………………………..…… (b) Explain why it is not recommended to use potassium carbonate and dilute sulfuric acid to prepare potassium sulfate using the method in 3(a). [1] ……………………………………………………………………………………………..……… ……………………………………………………………………………………………..……… [Total: 5 marks]

Page 8 of 11 [Turn over [ Turn over 4 Chemical substances and their physical properties Chemical substances have different physical properties based on its structure and chemical bonding. If the substance is insoluble in water, the electrical conductivity in its aqueous state was not tested. Table 4.1 gives information on the physical properties of some chemical substances. Table 4.1 chemical substance melting point / oC boiling point / oC electrical conductivity in solid state electrical conductivity in liquid state electrical conductivity in aqueous state A 1085 2562 good good - B 650 1091 good good - C 3550 4830 poor poor - D 851 1600 poor