1QA_Chemistry_AnyflipWM

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1 998 Chapter Form 4 Chapter 1 Introduction to Chemistry 1 Chapter 1 Redox Equilibrium 147 Chapter 2 Matter and the Atomic Structure 5 Chapter 2 Carbon Compound 163 Chapter 3 The Mole Concept, Chemical Formula and Equation 22 Chapter 3 Thermochemistry 175 Chapter 4 The Periodic Table of Elements 40 Chapter 4 Polymer 186 Chapter 5 Chemical Bond 58 Chapter 5 Consumer and Industrial Chemistry 196 Chapter 6 Acid, Base and Salt 80 Chapter 7 Rate of Reaction 111 Chapter 8 Manufactured Substances in Industry 135 SPM Model Test 207 Answers 234 F4n5 Q&A Chemi Content.indd 1 2/1/2023 1:53:53 PM PENERBIT ILMU BAKTI SDN. BHD.

1 SPM Model Test Answers Chapter Form 4 13 Chapter Form 5 13 1 1 1 Which of the following researches is related to Chemistry? A The behaviour of an amoeba in fl ood B The formation and properties of the black hole C The properties of light and the phenomena related to it D The production of vaccine for coronavirus disease (COVID-19) Answer: D The production of vaccine requires the use of various chemicals. 2 Which of the following tasks of a forensic scientist is related to Chemistry? A Study the police reports B Conduct research on blood tests C Find potential suspects of a crime D Analyse evidence from the crime scene Answer: D Knowledge in Chemistry is useful to analyse physical evidence found on the crime scene. Biological researches are related to Biology. Paper 1 Objective Questions 3 Which of the following careers requires the knowledge in Chemistry? A Cashier B Pharmacist C Accountant D Security guard Answer: B The manufacturing of medicine involves the knowledge in Chemistry and a lot of chemical reactions. 4 Which of the following processes involves a chemical reaction? A Slowing down a car by pressing the brake B The formation of rainbow after the rain C Dropping a stone from a tall building D Burning of some dried leaves Answer: D The burning of dried leaves involves breaking and formation of chemical bonds. 5 Which of the following chemicals can be easily found at home? A Hydrochloric acid B Sodium chloride C Liquid nitrogen D Nitric acid Answer: B Sodium chloride is the chemical name for common salt used for cooking. Development in Chemistry Field and Its Importance in Daily Life 1.1 Paper 1 Objective Questions 1.1 Development in 3 Which of the following careers Textbook Pages: 2 – 19 Theme 1: The Importance of Chemistry Introduction to Chemistry 1 CHAPTER Textbook Pages: 2 – 19 F4 Q&A Chemi 1(1-4).indd 1 2/1/2023 2:04:51 PM PENERBIT ILMU BAKTI SDN. BHD.

2 SPM Model Test Answers Chapter Form 4 Chapter Form 5 13 1 1 5 Which substance is an element? A Water B Titanium C Glucose D Carbon dioxide Answer: B Titanium is a metallic element. Scientifi c Investigation in Chemistry 1.2 6 During a scientifi c investigation, when should the results be recorded? A After the conclusion is made B After the variables are determined C When the experiment is conducted D Before the hypothesis is constructed Answer: C Results are recorded after the observations are made. Observations are made when the experiment is conducted. 7 Which statement is a hypothesis? A When the temperature of water is higher, the time taken for sugar to dissolve in it is shorter B To investigate how the temperature of water affects the solubility of sugar in it C The pink colour of the solution turns colourless D The white solid is magnesium oxide Answer: A The hypothesis shows the relationship between the manipulated and responding variables. Usage, Management and Handling of Apparatus and Materials 1.3 8 Wen Jiunn wants to investigate how the volume of water affects the mass of salt that can dissolve in it. Which apparatus is not required in the experiment? A Beaker B Thermometer C Electronic balance D Measuring cylinder Answer: B Measuring temperature is not involved in the experiment. Paper 2 Section A – Structured Questions 1 Chemical reactions are constantly occurring around us, and these reactions are related to Chemistry. (a) Give the defi nition of Chemistry. Chemistry is the branch of science that investigates matter and the interactions between them. [1 mark] (b) The following equation shows an important reaction that occurs in green plants. Carbon dioxide + Water → Glucose + Oxygen F4 Q&A Chemi 1(1-4).indd 2 2/1/2023 2:04:52 PM PENERBIT ILMU BAKTI SDN. BHD.

3 SPM Model Test Answers Chapter Form 4 13 Chapter Form 5 13 1 1 (i) Name the reaction. Photosynthesis [1 mark] (ii) Fill in the table to classify the substances in the equation into elements and compounds. Element Compound Oxygen Carbon dioxide Water Glucose [2 marks] (iii) State one important condition for the reaction named in 1(b)(i) to occur. The presence of sunlight. [1 mark] (c) Give one importance to learn Chemistry. Allow us to understand the properties of matters around us. [1 mark] 1 (b) (i) Photosynthesis of green plants converts carbon dioxide and water into glucose and oxygen gas. (ii) Elements consist of one type of atom only. Compounds are formed when two or more different types of atoms are combined chemically. (iii) Photosynthesis must occur in the presence of sunlight. (c) Chemistry is the fi eld of science involving the study of matters in terms of their structures, properties, compositions and interactions between them. Exam Tips 2 Scientifi c investigation is important for carrying out various researches. Diagram 1 shows several steps in the scientifi c investigation. Observation Constructing an inference X Constructing a hypothesis Identifying the variables Controlling the variables Diagram 1 F4 Q&A Chemi 1(1-4).indd 3 2/1/2023 2:04:52 PM PENERBIT ILMU BAKTI SDN. BHD.

4 SPM Model Test Answers Chapter Form 4 Chapter Form 5 13 1 1 (a) What is meant by scientific investigation? A systematic method of approaching a problem related to science. [1 mark] (b) What is step X? Identifying the problem [1 mark] (c) (i) Identify all the variables in scientific investigation. Manipulated variable, responding variable and fixed variable [2 marks] (ii) What is a hypothesis? A statement that shows the relationship between the manipulated variable and the responding variable of an investigation. [1 mark] Common Error Candidates often mistaken hypothesis with inference. Hypothesis relates the manipulated variable to the responding variable. Inference uses existing data to make a conclusion and explanation regarding a problem. (d) Aishah went to a dinner buffet with her friends. She saw the chicken curry is very oily and immediately told her friends that the chicken curry is unhealthy. Based on the scientific method, what is Aishah’s statement to her friends known as? Inference [1 mark] 2 (a) Scientifi c investigation is carried out to solve problems using scientifi c method. (b) Problem statement is made based on the inference of the investigation. (d) The statement is an inference. An inference is an early conclusion made based on observations. Exam Tips F4 Q&A Chemi 1(1-4).indd 4 2/1/2023 2:04:52 PM PENERBIT ILMU BAKTI SDN. BHD.

5 SPM Model Test Answers Chapter Form 4 13 Chapter Form 5 13 2 1 1 Which of the following statements is true about solids? A The particles in a solid contain a lot of energy B There are a lot of empty spaces between the particles C The particles in a solid are closely packed together D The attractive forces between the particles are very weak Answer: C The particles in a solid are arranged closely to each other with very limited spaces between the particles. The particles contain a very little energy and the attractive forces between the particles are very strong. 2 Which of the following processes releases heat? A Boiling B Melting C Freezing D Evaporation Answer: C During freezing process, a liquid turns to a solid and the heat energy is released to form attractive forces between the particles. Paper 1 Objective Questions 3 Diagram 1 shows the graph of temperature against time for the heating of naphthalene. 160 80 30 t 1 t 2 t 3 Time (s) Temperature (°C) Diagram 1 Why there is no change in the temperature from t 1 to t 2 ? A Heat is lost to the surroundings B The surroundings become cold for a while C The Bunsen burner were removed from heating the system D Heat is absorbed to overcome the attractive forces between the particles Answer: D During melting process, heat provided is absorbed by the naphthalene particles to overcome the attractive forces between the particles of solid naphthalene, so that liquid naphthalene can be formed. 2.1 Basic Concepts of Matter Textbook Pages: 22 – 39 Theme 2: Fundamentals of Chemistry 2 Matter and the Atomic Structure CHAPTER Textbook Pages: 22 – 39 F4 Q&A Chemi 2(5-21).indd 5 11/1/2023 5:14:22 PM PENERBIT ILMU BAKTI SDN. BHD.

6 SPM Model Test Answers Chapter Form 4 Chapter Form 5 13 2 1 4 Which statement explains why liquids are more diffi cult to be compressed compared to gases? A The stronger attractive forces between liquid particles prevent the effects of external forces B The gas particles are distributed very far from one another C The attractive forces between the gas particles are very weak D The gas particles can move freely Answer: B Gas can be compressed easily because there are a lot of empty spaces between the particles. 5 The following information is about substance Q. Freezing point: 268 °C Boiling point: 1 682 °C At which temperature does substance Q exists as a liquid? HOTS Analysing A 267 °C C 1 685 °C B 320 °C D 1 700 °C Answer: B Substance Q exists as a liquid at a temperature higher than its freezing point, but lower than its boiling point. 6 At room temperature, dry ice (solid carbon dioxide) turns directly into carbon dioxide gas. What is the name of the process that occurs? A Melting B Sublimation C Evaporation D Condensation Answer: B Sublimation is the process where a solid turns directly into a gas without becoming a liquid fi rst. 7 Methanol is made of CH3 OH molecules. Which of the following is true when liquid methanol evaporates? A The CH3 OH molecules break up into carbon, hydrogen and oxygen atoms B The attractive forces between the CH3 OH molecules become stronger C The distance between the CH3 OH molecules decreases D The CH3 OH molecules move faster Answer: D When a liquid evaporates into a gas, the particles gain more energy and move faster. 8 Which of the following substances is a compound? A C B Answer: C A compound contains two or more different types of atoms that are chemically bonded together. F4 Q&A Chemi 2(5-21).indd 6 11/1/2023 5:14:23 PM PENERBIT ILMU BAKTI SDN. BHD.

7 SPM Model Test Answers Chapter Form 4 13 Chapter Form 5 13 2 1 The Development of the Atomic Model 2.2 9 Which of the following scientists and their contributions in the development of the atomic model is paired correctly? Scientist Contribution A John Dalton Found protons B Ernest Rutherford Atomic theory C Niels Bohr Found neutrons D J.J. Thomson Found electrons Answer: D J.J. Thomson found electrons (negatively-charged particles) in 1897. 10 Diagram 2 shows the atomic model suggested by a scientist. Diagram 2 Who was the scientist? A Niels Bohr B J.J. Thomson C James Chadwick D Ernest Rutherford Answer: D In 1911, Ernest Rutherford proposed that an atom consists of a positively-charged nucleus located at the centre of the atom, and electrons circulate around the 2.3 Atomic Structure 11 The proton number of element R is 19. What is the electron arrangement of atom R? A 2.1.7 C 2.9.8 B 2.8.9 D 2.8.8.1 Answer: D There are 19 electrons in atom R. The fi rst shell can hold up to 2 electrons, the second and third shells can hold up to 8 electrons for an element with proton number less than 20. 12 Diagram 3 shows the standard representation of aluminium. 27 AI 13 Diagram 3 What is the number of protons, electrons and neutrons in an aluminium ion, Al3+? HOTS Analysing No. of protons No. of neutrons No. of electrons A 13 14 10 B 13 14 16 C 13 27 10 D 14 13 11 Answer: A Number of protons = Proton number = 13 Number of neutrons = Nucleon number – Proton number = 27 – 13 = 14 Number of electrons in aluminium ion, Al3+ = 13 – 3 = 10 F4 Q&A Chemi 2(5-21).indd 7 11/1/2023 5:14:23 PM PENERBIT ILMU BAKTI SDN. BHD.

8 SPM Model Test Answers Chapter Form 4 Chapter Form 5 13 2 1 13 Which of the following has the same number of protons and neutrons but lesser electrons than its neutrons? A 12 6C C 23 11 Na+ B 35 17Cl– D 24 12 Mg2+ Answer: D Number of protons = Proton number = 12 Number of neutrons = 24 – 12 = 12  Number of protons = Number of neutrons Number of electrons = 12 – 2 = 10 < Number of neutrons 14 Which of the following are the same in a sodium atom, Na and a sodium ion, Na+? I The number of protons II The number of electrons III The number of neutrons IV The number of shells fi lled with electrons A I and II C II and IV B I and III D III and IV Answer: B A sodium ion is formed when a sodium atom loses an electron. Therefore, sodium atom and sodium ion have different number of electrons. The number of protons and the number of neutrons remain unchanged. A sodium atom has 3 shells fi lled with electrons, but a sodium ion has only 2 shells fi lled with electrons. 15 The nucleus of atom X contains 72 neutrons. The X3+ ion has 64 electrons. What is the nucleon number of atom X? A 121 C 136 B 133 D 139 Answer: D Number of electrons in atom X = 64 + 3 = 67 = Number of protons in atom X Nucleon number of X = Number of protons + Number of neutrons 67 + 72 = 139 16 The proton number of element J is 17. Which of the following statements are true about element J? HOTS Analysing I The electron confi guration of atom J is 2.8.7 II Atom J has 7 valence electrons III The nucleus of atom J contains 17 neutrons IV The ion of element J has 17 electrons A I and II C II and IV B I and III D III and IV Answer: A The atom of element J contains 17 protons and 17 electrons. The electron arrangement of atom J is 2.8.7. 17 A particle has 3 electrons, 4 protons and 4 neutrons. What is the charge of the particle? A 0 B –1 C +1 D +4 Answer: C The particle contains one proton more than its electrons. Therefore, the particle has a charge of +1. F4 Q&A Chemi 2(5-21).indd 8 11/1/2023 5:14:23 PM PENERBIT ILMU BAKTI SDN. BHD.

9 SPM Model Test Answers Chapter Form 4 13 Chapter Form 5 13 2 1 18 An atom P forms P2+ ion. The P2+ ion contains 58 neutrons and 48 electrons. Which of the following is the standard representation for P? A 106 48 P C 106 50 P B 108 48 P D 108 50 P Answer: D The number of protons in an atom P = 48 + 2 = 50 Nucleon number of atom P = 50 + 58 = 108 2.4 Isotopes and Its Uses 19 Chlorine-35 and chlorine-37 are the isotopes of chlorine. What is the similarity between chlorine-35 and chlorine-37? A The density of the atoms B The number of electrons C The number of neutrons D The mass of the atoms Answer: B Isotopes have the same number of protons and electrons. Isotopes have the same chemical properties but different physical properties. 20 An engineer wants to detect the location of leakage in underground pipes. Which isotope is the most suitable to be used by the engineer? HOTS Applying A Cobalt-60 C Iodine-131 B Carbon-14 D Sodium-24 Answer: D Candidates must remember the uses of isotopes in various fi elds such as medicine, archaeology, engineering and agriculture. 21 Bromine-79 and bromine-81 are the isotopes of bromine. The number of neutrons in bromine-79 is 44. How many neutrons are there in a bromine-81 atom? HOTS Analysing A 35 C 44 B 37 D 46 Answer: D The number of protons in bromine-79 = 79 – 44 = 35 Isotopes have the same number of protons.  Number of neutrons in bromine-81 = 81 – 35 = 46 22 Carbon-14 is an isotope of carbon. What is the use of carbon-14 isotope? HOTS Applying A To kill and destroy cancer cells B To determine the age of fossils C As nuclear fuel to generate electricity D For monitoring the thickness of paper produced Answer: B Carbon-14 is used in archaeology fi eld to determine the age of fossils and artifacts. F4 Q&A Chemi 2(5-21).indd 9 11/1/2023 5:14:23 PM PENERBIT ILMU BAKTI SDN. BHD.

10 SPM Model Test Answers Chapter Form 4 Chapter Form 5 13 2 1 Paper 2 Section A – Structured Questions 1 Diagram 1.1 shows the apparatus set-up for an activity carried out by a group of students to determine the melting point of naphthalene in the school laboratory. Diagram 1.2 shows the graph of temperature against time obtained from the results of the activity. Naphthalene Heat Time (s) Thermometer Retort stand Temperature (°C) 150 80 30 t 1 t 2 Naphthalene Heat Thermometer Retort stand Diagram 1.1 Diagram 1.2 (a) There is a mistake done by the students in the apparatus set-up shown in Diagram 1.1. (i) Identify the mistake. HOTS Analysing The boiling tube containing naphthalene is heated directly. [1 mark] (ii) Suggest a way to correct the mistake. HOTS Applying Use a water bath to heat up the boiling tube containing naphthalene. [1 mark] 23 Table 3 shows the percentage abundance of two isotopes of element T. Nucleon number Percentage abundance (%) 24 70 26 30 Table 3 What is the relative atomic mass of T? HOTS Evaluating A 24.6 C 49.2 B 25.4 D 50.8 Answer: A Relative atomic mass of T = (24 × 70) + (26 × 30) (30 + 70) = 24.6 F4 Q&A Chemi 2(5-21).indd 10 11/1/2023 5:14:23 PM PENERBIT ILMU BAKTI SDN. BHD.

11 SPM Model Test Answers Chapter Form 4 13 Chapter Form 5 13 2 1 Common Error Candidates must remember that naphthalene cannot be heated directly. It must be heated in the water bath. Heating of naphthalene in the water bath is shown in the diagram. The rubber stopper must be removed during heating. Boiling tube Water Naphthalene Thermometer (iii) State the reason why the correction suggested in 1(a)(ii) must be carried out. HOTS Analysing To make sure that the heating of naphthalene is uniform and for safety reason, because naphthalene is a highly fl ammable substance. [1 mark] (b) What type of particle is found in naphthalene? Molecules [1 mark] (c) Based on Diagram 1.2, (i) state the melting point of naphthalene. 80 °C [1 mark] Common Error The answer is not accepted if the correct unit (°C) is not written. (ii) explain why the temperature remains constant from t 1 to t 2 . HOTS Analysing The heat energy is absorbed by the particles to overcome the attractive forces between the particles of solid naphthalene. Hence, it can melt and becomes liquid naphthalene. [2 marks] 1 (a) (i) In this activity, the boiling tube containing naphthalene cannot be heated directly with a Bunsen burner. It will produce poisonous vapours. (ii) Water bath is used because, the melting point of naphthalene is less than 100 °C. For substances with melting point of more than 100 °C, an oil bath is used. (iii) Heating with water bath allows the heat to be uniformly distributed from all around the boiling tube. Exam Tips F4 Q&A Chemi 2(5-21).indd 11 11/1/2023 5:14:24 PM PENERBIT ILMU BAKTI SDN. BHD.

12 SPM Model Test Answers Chapter Form 4 Chapter Form 5 13 2 1 (b) Naphthalene exists as covalent molecules with the chemical formula C10H8 . (c) (i) The temperature is constant at 80 °C. (ii) Heat energy is not converted to kinetic energy and the rate of vibration of the particles remains almost constant. As a result, the temperature remains constant. 2 Diagram 2 shows the standard representation of a potassium atom. 39 K 19 Diagram 2 (a) What are represented by the numbers 19 and 39? (i) 19 Proton number [1 mark] (ii) 39 Nucleon number [1 mark] (b) How many neutrons are there in a potassium atom? 39 – 19 = 20 neutrons [1 mark] (c) Potassium atoms can form potassium ions, K+ . (i) Briefl y explain how a potassium ion is formed from a potassium atom. HOTS Analysing A potassium atom with the electron arrangement of 2.8.8.1, will lose one electron to form a potassium ion, K+ . [1 mark] (ii) Write the electron arrangement of potassium ion, K+ . 2.8.8 [1 mark] (d) Another atom of potassium contains more neutrons but the same number of protons and electrons as the atom shown in Diagram 2. What is the relationship between these two potassium atoms? HOTS Analysing The atoms are isotopes. [1 mark] F4 Q&A Chemi 2(5-21).indd 12 11/1/2023 5:14:24 PM PENERBIT ILMU BAKTI SDN. BHD.

13 SPM Model Test Answers Chapter Form 4 13 Chapter Form 5 13 2 1 2 (a) (i) In the standard representation of atom K, Proton number = Number of protons in the nucleus of an atom (ii) Nucleon number = Number of neutrons + Number of protons (b) Number of neutrons = Nucleon number – proton number (c) (ii) The electron arrangement of a potassium atom, K is 2.8.8.1. One electron is donated. Therefore, the electron arrangement of a potassium ion, K+ is 2.8.8. (d) Isotopes have the same number of protons but different number of neutrons. Therefore, isotopes have the same proton number but different nucleon numbers. Exam Tips 39 K 19 Nucleon number Proton number 3 Table 1 shows the chemical formulae of several substances. Substance Chemical formula Carbon dioxide CO2 Mercury Hg Iodine I2 Sodium chloride NaCl Water H2 O Table 1 (a) Based on Table 1, which substance (i) is an element? Mercury/ Iodine [1 mark] Common Error Candidates assumed that elements are only atoms. An element can be an atom or a molecule that contains only one type of atom. (ii) consists of ions? HOTS Analysing Sodium chloride [1 mark] (iii) is a compound that exists as a liquid at room temperature? HOTS Analysing Water [1 mark] F4 Q&A Chemi 2(5-21).indd 13 11/1/2023 5:14:24 PM PENERBIT ILMU BAKTI SDN. BHD.

14 SPM Model Test Answers Chapter Form 4 Chapter Form 5 13 2 1 (b) In the space provided, draw the arrangement of particles of mercury at room temperature. HOTS Applying [1 mark] Common Error Candidates are confused with the arrangement of particles in solid, liquid and gas. In solid: Particles are closely packed together. In liquid: Particles are in random, but some are in contact with each other. In gas: Particles are far from one another. (c) Solid carbon dioxide is also known as dry ice. When dry ice is heated, it turns into carbon dioxide gas directly. (i) Name the process that occurs. Sublimation [1 mark] (ii) Identify another substance in Table 1 that undergoes the same process. Iodine [1 mark] (iii) Briefl y explain why dry ice is preferred to store food such as icecream at a lower temperature compared to ice. HOTS Applying Dry ice turns into a gas directly when heated and do not leave a messy liquid residue. [1 mark] 3 (a) (i) Mercury and iodine are elements, because they contain only one type of atom. (ii) Sodium chloride is made of a positive sodium ion, Na+ and a negative chloride ion, Cl–. (iii) Water has a melting point of 0 °C and a boiling point of 100 °C. (b) Mercury has a melting point of –38.8 °C and a boiling point of 356.7 °C. Mercury exists as a liquid at room temperature. (c) (i) Sublimation is a process where a solid turns directly into a gas and vice versa without becoming a liquid fi rst. (ii) Iodine also turns directly into vapour when solid iodine is heated. Exam Tips F4 Q&A Chemi 2(5-21).indd 14 11/1/2023 5:14:24 PM PENERBIT ILMU BAKTI SDN. BHD.

15 SPM Model Test Answers Chapter Form 4 13 Chapter Form 5 13 2 1 4 Diagram 3 shows the standard representation for two isotopes of boron. 10 B 5 11 B 5 Boron-10 Boron-11 Diagram 3 (a) What is the meaning of isotopes? Isotopes are atoms of the same element that have the same proton number but different nucleon numbers. [1 mark] (b) (i) Compare the chemical properties of both isotopes of boron. Both have the same chemical properties. [1 mark] Common Error Candidates assumed that isotopes have the same physical and chemical properties. Isotopes have the same chemical properties but different physical properties. (ii) Briefl y explain your answer in 4(b)(i). Both have the same number of protons and electrons. [1 mark] (c) Draw the electron arrangement of a boron atom. HOTS Applying B [1 mark] (d) The natural abundance of boron-10 is 20% and boron-11 is 80%. Calculate the relative atomic mass of boron. Relative atomic mass of boron = (10 × 20) + (11 × 80) (20 + 80) = 10.8 [2 marks] F4 Q&A Chemi 2(5-21).indd 15 11/1/2023 5:14:24 PM PENERBIT ILMU BAKTI SDN. BHD.

16 SPM Model Test Answers Chapter Form 4 Chapter Form 5 13 2 1 (e) An archaeologist found the fossil of a dead plant and he wanted to determine the age of the fossil. Which isotope is the most suitable to be used by the archaeologist? HOTS Applying Carbon-14 [1 mark] 4 (b) (ii) Isotopes have the same number of valence electrons. The number of valence electrons determines the chemical properties of an atom. (c) Boron atom has 5 electrons. The fi rst shell is fi lled with a maximum number of 2 electrons and the remaining 3 electrons are fi lled into the second shell. In an atom, Proton number = Number of protons = Number of electrons (d) Use the following equation: RAM = (Nucleon number of isotope 1 × % abundance of isotope 1) + (Nucleon number of isotope 2 × % abundance of isotope 2) (Total % abundance) (e) Candidates must remember the uses of common isotopes such as cobalt-60, iodine-131, phosphorus-32, uranium-235, carbon-14, lead-210, Exam Tips 5 Diagram 4 shows the information about atom Z. • Has 3 shells fi lled with electrons. • Has 1 valence electron. • There are 12 neutrons in its nucleus. Diagram 4 (a) (i) Write the electron arrangement of atom Z. HOTS Analysing 2.8.1 [1 mark] (ii) Name the scientist who proposed that electrons circulate the nucleus of an atom in fi xed shells. Niels Bohr [1 mark] (b) (i) How many protons are there in an atom Z? Briefly explain your answer. HOTS Analysing 11 protons. An atom has the same number of protons and electrons. [2 marks] (ii) Determine the nucleon number of atom Z. 23 [1 mark] F4 Q&A Chemi 2(5-21).indd 16 11/1/2023 5:14:24 PM PENERBIT ILMU BAKTI SDN. BHD.

17 SPM Model Test Answers Chapter Form 4 13 Chapter Form 5 13 2 1 (iii) Write the standard representation of atom Z. 23 11 Z [2 marks] 5 (a) (i) The third shell of atom Z is the valence shell which is occupied by only one electron. (ii) Bohr’s Atomic Model (b) (i) An atom is a neutral particle. Therefore, the number of protons equals the number of electrons (ii) Nucleon number = Number of protons + Number of neutrons = 11 + 12 = 23 (iii) The standard representation of an atom is written as A Z X, where A = nucleon number Z = proton number Exam Tips Paper 2 Section B & C – Essay Questions 6 (a) Diagram 1.1 shows a balloon containing some air. Diagram 1.1 (i) Air is an example of matter. Briefly explain the above statement. [2 marks] (ii) Matter consists of tiny particles. By giving appropriate examples, list three types of particles found in matter. Identify the differences between the particles listed. HOTS Analysing [6 marks] F4 Q&A Chemi 2(5-21).indd 17 11/1/2023 5:14:25 PM PENERBIT ILMU BAKTI SDN. BHD.

18 SPM Model Test Answers Chapter Form 4 Chapter Form 5 13 2 1 (b) Diagram 1.2 shows a burning candle. The physical state of the candle changes during the burning process. Heat from the fl ame causes the candle to turn into liquid wax Liquid wax cools down and turns back into solid Diagram 1.2 (i) Name the two processes shown in Diagram 1.2. [2 marks] (ii) Describe the changes that occur during the processes named in 6(b)(i). HOTS Analysing Your description must include the following information: • Change in the energy content of the wax particles. • Change in the attractive forces between the wax particles. • Change in the movement of the wax particles. • Change in the empty spaces between the wax particles. [8 marks] Answers 6 (a) (i) A matter is defi ned as any substance with mass and occupies space. Air has mass and can occupy space. Therefore, air is a matter. (ii) Atoms, molecules and ions are the three types of particles found in matter. Atoms are single neutral particles that do not form any chemical bond with other particles. An example of atom is copper atom, Cu. Molecules are neutral particles formed when two or more atoms are combined chemically. An example of molecule is water molecule, H2 O. Ions are charged particles formed when a neutral particle gains or loses electrons. An example of ion is sodium ion, Na+ . . Common Error Candidates assumed that matter only consists of atoms. Matter consists of atoms, molecules and ions. Candidates must give at least one example for each type of particle (b) (i) The process where candle melts into liquid wax is known as melting, while the process where liquid wax turns back to solid is known as freezing. F4 Q&A Chemi 2(5-21).indd 18 11/1/2023 5:14:25 PM PENERBIT ILMU BAKTI SDN. BHD.

19 SPM Model Test Answers Chapter Form 4 13 Chapter Form 5 13 2 1 6 (a) (i) Give the defi nition of matter and relate to why air is a matter. (ii) Candidates are required to list the three types of particles found in matter. Candidates must differentiate clearly between the particles listed. Candidates must give an example for each type of particle. (b) (i) Candidates should know the processes of conversion among the states of matter. (ii) Construct a table to present your answers so that your answer looks more systematic. Exam Tips 7 Diagram 2 shows the structure of atom X. Neutron Proton Electron Diagram 2 An atom consists of protons, neutrons and electrons. Protons, neutrons and electrons are known as subatomic particles. (a) (i) State the properties of subatomic particles in terms of their relative charges and relative masses. [6 marks] Melting process Freezing process The energy content of the wax particles increases The energy content of the wax particles decreases The attractive forces between the wax particles become weaker The attractive forces between the wax particles become stronger The wax particles start to move faster and more freely The wax particles start to move slower and more bounded The empty spaces between the wax particles become bigger The empty spaces between the wax particles become smaller (ii) F4 Q&A Chemi 2(5-21).indd 19 11/1/2023 5:14:25 PM PENERBIT ILMU BAKTI SDN. BHD.

20 SPM Model Test Answers Chapter Form 4 Chapter Form 5 13 2 1 (ii) Atom X in Diagram 2 consists of 8 protons, 8 electrons and 9 neutrons. Determine the proton number and nucleon number of atom X. Write the standard representation of atom X. HOTS Evaluating [4 marks] (b) A student carried out an activity to determine the melting point of substance V. Substance V is heated from the temperature of 30 °C to 80 °C in a water bath. Substance V is a solid at room temperature and a liquid at 80 °C. Based on the description given, sketch the graph of temperature against time for the heating of substance V and mark the melting point with the letter ‘T’. Describe the graph sketched in terms of the physical state of substance V and the movement of particles in substance V. HOTS Analysing [10 marks] Answers 7 (a) (i) Common Error Candidates are confused with the terms relative and actual values. The relative atomic mass of an element refers to the weight in grams of the number of atoms of the element contained in 12 g of carbon-12. (ii) Proton number = Number of protons = 8 Nucleon number = Number of protons + Number of neutrons = 17 Standard representation: 17 8 X Common Error Standard representation: A Z X, where A = nucleon number Z = proton number Do not misplace A and Z. Subatomic particle Proton Neutron Electron Relative charge +1 0 –1 Relative mass 1 1 1 1 840 F4 Q&A Chemi 2(5-21).indd 20 11/1/2023 5:14:25 PM PENERBIT ILMU BAKTI SDN. BHD.

21 SPM Model Test Answers Chapter Form 4 13 Chapter Form 5 13 2 1 7 (a) (ii) The nucleon number is the total number of protons and neutrons. The standard representation is written as A Z X, where A = nucleon number Z = proton number (b) Heating curve shows and increasing of temperature over time. Straight line indicates that there is no change occurs in the temperature. The graph starts from 30 °C and not 0 °C because the activity is carried out at room temperature. The melting point, T is marked on the left side of the temperature axis. The fi nal temperature of 80 °C should also be marked clearly. Descriptions must concentrate on the physical states and the movement of particles in substance V along the line of graph sketched. Exam Tips (b) Temperature (°C) Time (s) 0 t1 t 2 t 3 80 T 30 Common Error Candidates must show the horizontal line during the melting of substance V. The axes of the graph must be labelled correctly. From 0 s to t 1 , substance V exists as a solid. The particles in substance V vibrate faster as the heat energy is converted into kinetic energy. From t 1 to t 2 , substance V exists as a mixture of solid and liquid. The vibration of particles in substance V remains almost constant temporarily because the heat energy is used to overcome the attractive forces between the particles of solid substance V. From t 2 to t 3 , substance V exists as a liquid. The particles in substance V vibrate faster as the heat energy is converted into kinetic energy. F4 Q&A Chemi 2(5-21).indd 21 11/1/2023 5:14:25 PM PENERBIT ILMU BAKTI SDN. BHD.

22 SPM Model Test Answers Chapter Form 4 Chapter Form 5 13 3 1 1 The relative atomic mass of aluminium is 27 and silver is 108. How many aluminium atoms have the same mass as one silver atom? A 2 atoms C 4 atoms B 3 atoms D 5 atoms Answer: C Number of Al atoms = 108 27 = 4 atoms 2 Haloperidol is a psychotic drug with the molecular formula C21H23ClFNO2 . What is the relative molecular mass of haloperidol? [Relative atomic mass: H = 1, C = 12, N = 14, O = 16, F = 19, Cl = 35.5] A 359.5 C 387.5 B 375.5 D 398.5 Answer: B Relative molecular mass is the sum of relative atomic masses of all atoms in a compound. RMM = (21 × 12) + (23 × 1) + 35.5 + 19 + 14 + (2 × 16) = 375.5 3 Cisplatin, Pt(NH3 )2 Cl2 is a compound that can be used to treat various types of cancer. The relative formula mass of cisplatin is 300. Paper 1 Objective Questions What is the relative atomic mass of platinum? [Relative atomic mass: H = 1, N = 14, Cl = 35.5] A 195 C 212 B 209 D 229 Answer: A Relative atomic mass of Pt = x Relative formula mass of cisplatin, x + 2[14 + (3 × 1)] + (2 × 35.5) = 300  x = 195 4 The chemical formula of hydrated copper(II) sulphate is CuSO4 •xH2 O. Given that the relative formula mass of hydrated copper(II) sulphate is 250. What is the value of x? [Relative atomic mass: Cu = 64, S = 32, O = 16, H = 1] A 2 C 4 B 3 D 5 Answer: D RFM of CuSO4•xH2O = 250 64 + 32 + (4 × 16) + x[(2 × 1) + 16] = 250 18x = 90  x = 5 5 How many times is 8 ethanoic acid, C2 H4 O2 molecules heavier than 3 calcium atoms, Ca? [Relative atomic mass: H = 1, C = 12, O = 16, Ca = 40] A 2 times C 12 times B 4 times D 1.5 times Relative Atomic Mass and Relative Molecular Mass 3.1 Textbook Pages: 42 – 75 Theme 2: Fundamentals of Chemistry The Mole Concept, Chemical 3 Formula and Equation CHAPTER F4 Q&A Chemi 3(22-39).indd 22 11/1/2023 5:15:27 PM PENERBIT ILMU BAKTI SDN. BHD.

23 SPM Model Test Answers Chapter Form 4 13 Chapter Form 5 13 3 1 Answer: B RMM of ethanoic acid = (2 × 12) + (4 × 1) + (2 × 16) = 60 Number of times heavier = 8 × RMM of ethanoic acid 3 × RAM of calcium = 8 × 60 3 × 40 = 4 times 3.2 Mole Concept 6 The relative atomic mass of elements P and Q are both 20. Which of the following statements is true based on the information given above? A Atom P and atom Q have the same size B Both atom P and atom Q have the same electron arrangement C 20 g of element P have the same number of atoms as 20 g of element Q D Both atom P and atom Q have 10 protons and 10 neutrons in their nucleus Answer: C 20 g of P and 20 g of Q have the same number of moles, because they have the same relative atomic mass. Number of atoms = Number of moles × Avogadro constant 7 The following statement is about one mole of a substance. One mole of a substance contains the same number of particles as the number of atoms in x g of Y. Based on the statement given, what are x and Y? x Y A 4.0 Helium-4 B 1.0 Hydrogen-1 C 12.0 Carbon-12 D 16.0 Oxygen-16 Answer: C One mole of a substance is defined as the quantity of the substance that contains the same number of particles as the number of atoms in 12.0 g of carbon-12. 8 Table 1 shows the relative atomic mass of two elements. Element Relative atomic mass Iron 56 Lithium 7 Table 1 Which of the following statements are true? I One mole of iron has 8 times more number of atoms than one mole of lithium II One iron atom has the same number of protons as 8 lithium atoms III One iron atom is 8 times heavier than one lithium atom IV 56 g of iron has the same number of atoms as 7 g of lithium A I and II B I and III C II and IV D III and IV F4 Q&A Chemi 3(22-39).indd 23 11/1/2023 5:15:27 PM PENERBIT ILMU BAKTI SDN. BHD.

24 SPM Model Test Answers Chapter Form 4 Chapter Form 5 13 3 1 Answer: D • The number of times of one iron atom heavier than one lithium atom = 56 g 7 g = 8 times • 56 g of iron and 7 g of lithium have the same number of moles. Therefore, they have the same number of atoms. 9 Which of the following gases has the same volume as 28 grams of nitrogen gas, N2 at STP? [Relative atomic mass: H = 1, C = 12, N = 14, O = 16, S = 32, Cl = 35.5] A 3 g of hydrogen gas, H2 B 35.5 g of chlorine gas, Cl2 C 44 g of carbon dioxide, CO2 D 32 g of sulphur dioxide, SO2 Answer: C Number of moles of N2 = 28 2 × 14 = 28 28 = 1 mol Number of moles of CO2 = 44 12 + (2 × 16) = 44 44 = 1 mol Gases have the same volume under the same conditions if they have the same number of moles. 10 Which of the following has the same number of atoms as 8 grams of copper? [Relative atomic mass: O = 16, Mg = 24, Ca = 40, Fe = 56, Cu = 64; Avogadro constant = 6.02 × 1023 mol–1] A 3.0 grams of magnesium, Mg B 8.0 grams of oxygen gas, O2 C 10.0 grams of calcium, Ca D 3.5 grams of iron, Fe Answer: A Number of Cu atoms = 8 64 × 6.02 × 1023 = 7.525 × 1022 atoms Number of Mg atoms = 3 24 × 6.02 × 1023 = 7.525 × 1022 atoms 11 A chemical reaction releases 480 cm3 of oxygen gas at room conditions. What is the number of moles of oxygen gas released from the reaction? [1 mole of any gas occupies 24 dm3 at room conditions] A 0.020 mol B 0.021 mol C 20 mol D 21 mol Answer: A Number of moles of oxygen gas = 480 24 000 = 0.020 mol 12 The mass of 0.03 mol naphthalene is 3.84 g. What is the relative molecular mass of naphthalene? A 78 B 115 C 128 D 384 Answer: C Number of moles = Mass (g) RMM 0.03 = 3.84 RMM  RMM of naphthalene = 3.84 0.03 = 128 F4 Q&A Chemi 3(22-39).indd 24 11/1/2023 5:15:28 PM PENERBIT ILMU BAKTI SDN. BHD.

25 SPM Model Test Answers Chapter Form 4 13 Chapter Form 5 13 3 1 13 Diagram 1 shows two beakers, P and Q containing 300 g of water and 300 g of ethanol respectively. 300 g of water, H2 O P Q 300 g of ethanol, C2 H6 O Diagram 1 Which statement is true? [Relative atomic mass: H = 1, C = 12, O = 16] A The number of water molecules in beaker P and the number of ethanol molecules in beaker Q are the same B There are lesser water molecules in beaker P than the number of ethanol molecules in beaker Q C There are more water molecules in beaker P than the number of ethanol molecules in beaker Q D The relative molecular mass of water is equal to the relative molecular mass of ethanol Answer: C Number of moles of water in beaker P = 300 18 = 16.67 mol Number of moles of ethanol in beaker Q = 300 46 = 6.52 mol There are more water molecules because it has a higher number of moles. 14 There are three times more atoms in x g of aluminium than in 1.38 g of sodium. What is the value of x? [Relative atomic mass: Na = 23, Al = 27] A 0.54 g C 3.53 g B 1.62 g D 4.86 g Answer: D Both aluminium and sodium are made up of atoms. Number of moles of Al = 3 × Number of moles of Na x 27 = 3 × 1.38 23  x = 4.86 g 15 A balloon contains a mixture of nitrogen gas, N2 and helium gas, He at room conditions. The volume of the balloon is 1.8 dm3 . If the mass of nitrogen in the balloon is 1.4 g, what is the mass of helium in the balloon? [Relative atomic mass: He = 4, N = 14; 1 mole of any gas occupies 24 dm3 at room conditions] A 0.04 g C 0.10 g B 0.08 g D 0.20 g Answer: C Number of moles of N2 in the balloon = 1.4 28 = 0.05 mol Volume occupied by N2 in the balloon = 0.05 × 24 dm3 = 1.2 dm3  Volume occupied by He = (1.8 – 1.2) dm3 = 0.6 dm3 Number of moles of He in the balloon = 0.6 24 = 0.025 mol  Mass of He in the balloon = 0.025 × 4 = 0.1 g F4 Q&A Chemi 3(22-39).indd 25 11/1/2023 5:15:28 PM PENERBIT ILMU BAKTI SDN. BHD.

26 SPM Model Test Answers Chapter Form 4 Chapter Form 5 13 3 1 3.3 Chemical Formula 16 Compound X contains carbon, hydrogen and oxygen. Which of the following is the empirical formula of X? A CH3 O C C4 H6 O2 B C2 H4 O2 D C6 H12O6 Answer: A Empirical formula shows the simplest ratio of the number of atoms for every element in a molecule of a compound. 17 The empirical formula of an organic compound is CH3 O and its relative molecular mass is 62. What is the molecular formula of the compound? [Relative atomic mass: H = 1, C = 12, O = 16] A CH3 O C C3 H9 O3 B C2 H6 O2 D C4 H12O4 Answer: B Assume that the molecular formula = (CH3O)n Relative molecular mass of (CH3O)n = 62 n × [12 + (3 × 1) + 16] = 62  n = 62 31 = 2 Molecular formula = (CH3O)2 = C2H6O2 18 Table 2 shows the chemical formulae of chromium chloride and zinc carbonate. Compound Chromium chloride Zinc carbonate Chemical formula CrCl3 ZnCO3 Table 2 What is the chemical formula of chromium carbonate? A CrCO3 C Cr2 (CO3 )3 B Cr(CO3 )2 D Cr3 (CO3 )2 Answer: C The formula of chromium ion is Cr3+ and the formula of carbonate ion is CO3 2–. 3.4 Chemical Equation 19 Which of the following chemical equations is balanced correctly? A Pb(NO3 )2 + K2 CO3 → PbCO3 + KNO3 B CaCO3 + HCl → CaCl2 + CO2 + H2 O C NaOH + HNO3 → NaNO3 + H2 O D CH4 + O2 → CO2 + H2 O Answer: C A balanced chemical equation has the same number of atoms of every element on both sides. 20 The following chemical equation shows the complete combustion of propane, C3 H8 . C3 H8 (g) + 5O2 (g) → 3CO2 (g) + 4H2 O(l) Which statement is true about the equation? A 1.0 g of C3 H8 reacts with 5.0 g of O2 to produce 3.0 g of CO2 and 4.0 g of H2 O B 0.5 mole of C3 H8 reacts with 2.5 moles of O2 to produce 1.5 moles of CO2 and 2.0 moles of H2 O C The number of moles of the reactants is equal to the number of moles of the products F4 Q&A Chemi 3(22-39).indd 26 11/1/2023 5:15:28 PM PENERBIT ILMU BAKTI SDN. BHD.

27 SPM Model Test Answers Chapter Form 4 13 Chapter Form 5 13 3 1 D The total number of particles before the reaction is the same as the total number of particles after the reaction Answer: B From the equation, 1.0 mole of C3H8 reacts with 5.0 moles of O2 to produce 3.0 moles of CO2 and 4.0 moles of H2O. The number of moles of each substance in the equation can be divided or multiplied by the same factor, as long as the ratio remains the same. 21 When potassium is heated in oxygen, potassium oxide is produced as shown in the following equation. 4K(s) + O2 (g) → 2K2 O(s) A student reacted 0.78 g of potassium with excess oxygen gas. What is the mass of potassium oxide produced? [Relative atomic mass: K = 39, O = 16] A 0.470 g B 0.940 g C 0.975 g D 1.880 g Answer: B Number of moles of K used = 0.78 39 = 0.02 mol From the equation, 4 moles of K react to produce 2 moles of K2O.  0.02 mole of K reacts to produce 0.01 mole of K2O. RFM of K2O = 2(39) + 16 = 94  Mass of K2O = 0.01 × 94 = 0.940 g 22 Magnesium ribbon is dissolved in dilute hydrochloric acid according to the following chemical equation. Mg(s) + 2HCl(aq) → MgCl2 (aq) + H2 (g) In an experiment, 0.6 g of magnesium dissolved completely in a beaker containing excess hydrochloric acid. What is the volume of hydrogen gas produced at STP? [Relative atomic mass: Mg = 24; 1 mole of any gas occupies the volume of 22.4 dm3 at STP] A 0.56 dm3 B 0.60 dm3 C 1.12 dm3 D 1.20 dm3 Answer: A Number of moles of Mg = 0.6 24 = 0.025 mol From the equation, 1 mole of Mg reacts to produce 1 mole of H2.  0.025 mole of Mg reacts to produce 0.025 mole of H2. Volume of H2 at STP = 0.025 × 22.4 dm3 = 0.56 dm3 23 Ammonia is produced from the reaction between nitrogen and hydrogen as shown in the chemical equation below. N2 (g) + 3H2 (g) → 2NH3 (g) What is the mass of ammonia produced if 7.0 g of nitrogen gas is reacted with 7.0 g of hydrogen gas? [Relative atomic mass: H = 1, N = 14] F4 Q&A Chemi 3(22-39).indd 27 11/1/2023 5:15:28 PM PENERBIT ILMU BAKTI SDN. BHD.

28 SPM Model Test Answers Chapter Form 4 Chapter Form 5 13 3 1 A 2.13 g C 39.67 g B 8.50 g D 89.25 g Paper 2 Section A – Structured Questions 1 Table 1 shows the relative atomic mass of several elements. Element Carbon, C Nitrogen, N Potassium, K Iron, Fe Relative atomic mass 12 14 39 56 Table 1 (a) State the meaning of (i) relative atomic mass. The ratio of the average mass of an atom to 1 12 of the mass of a carbon-12 atom. [1 mark] (ii) relative molecular mass. The ratio of the average mass of a molecule to 1 12 of the mass of a carbon-12 atom. [1 mark] (b) Based on the information in Table 1, calculate (i) how many times is 3 iron atoms heavier than 2 nitrogen atoms. HOTS Applying Number of times heavier = 3 × RAM of Fe 2 × RAM of N = 3 × 56 2 × 14 = 6 times [2 marks] Answer: B Number of moles of N2 = 7 28 = 0.25 mol Number of moles of H2 = 7 2 = 3.5 mol From the equation, 1 mole of N2 reacts with 3 moles of H2.  0.25 mole of N2 reacts with 0.75 mole of H2 (H2 is in excess). From the equation, 1 mole of N2 reacts to produce 2 moles of NH3.  0.25 mole of N2 reacts to produce 0.5 mole of NH3. RMM of NH3 = 14 + 3(1) = 17  Mass of NH3 produced = 0.5 × 17 = 8.50 g F4 Q&A Chemi 3(22-39).indd 28 11/1/2023 5:15:29 PM PENERBIT ILMU BAKTI SDN. BHD.

29 SPM Model Test Answers Chapter Form 4 13 Chapter Form 5 13 3 1 (ii) the number of carbon atoms that has the same mass as 4 potassium atoms. Assume the number of carbon atoms = n  n × RAM of C = 4 × RAM of K 12n = 4 × 39 n = 13 atoms [2 marks] (c) The chemical formula of potassium hexacyanoferrate(II) is K4 Fe(CN)6 . Find the relative formula mass of potassium hexacyanoferrate(II). RFM of K4 Fe(CN)6 = (4 × 39) + 56 + 6(12 + 14) = 368 [1 mark] 1 (b) Relative atomic mass can be used to represent the mass of an atom when comparing the masses of atoms. (c) Relative molecular mass or relative formula mass of a substance is the sum of relative atomic masses of all atoms in the substance. Exam Tips 2 Diagram 1 shows the volume and mass of gas X in a balloon at room temperature and pressure. Volume = 3.6 dm3 Mass = 6.6 g Diagram 1 (a) The following equations show the relationship between the two quantities of gas X in the balloon. Fill in the blanks to complete the relationship shown. (i) Number of moles of gas X = Volume of gas X (____________________) Molar volume [1 mark] (ii) Number of moles of gas X = Mass of gas X (____________________) Molar mass of gas X [1 mark] F4 Q&A Chemi 3(22-39).indd 29 11/1/2023 5:15:29 PM PENERBIT ILMU BAKTI SDN. BHD.

30 SPM Model Test Answers Chapter Form 4 Chapter Form 5 13 3 1 8 (a) (i) By 1 (a) In w 9 (a) Dia (b) Using the relationship in 2(a), calculate the relative molecular mass of gas X. [1 mole of any gas occupies the volume of 24 dm3 at room conditions] Number of moles of gas X = 3.6 24 = 0.15 mol 6.6 RMM of gas X = 0.15 mol � RMM of gas X = 6.6 0.15 = 44 [2 marks] (c) How many particles of gas X are there in the balloon? [Avogadro constant: 6.02 × 1023 mol–1] Number of particles = 0.15 × 6.02 × 1023 = 9 x 1022 molecules [1 mark] 2 (a) (i) Number of moles = Volume of gas Molar volume (ii) Number of moles = Mass Molar mass (b) Number of moles = Volume of gas Molar volume = Mass of gas Molar mass (c) Number of particles = Number of moles × Avogadro constant Exam Tips 3 (a) Give the defi nition of (i) empirical formula. The chemical formula that shows the simplest ratio of the number of atoms in a compound. [1 mark] (ii) molecular formula. The chemical formula that shows the actual number of atoms in a compound. [1 mark] (b) An organic compound consists of carbon, hydrogen and nitrogen elements. Table 2 shows the percentages of the elements, by mass, in the organic compound. Element Carbon, C Hydrogen, H Nitrogen, N Percentage by mass (%) 28.57 4.76 66.67 Table 2 F4 Q&A Chemi 3(22-39).indd 30 11/1/2023 5:15:29 PM PENERBIT ILMU BAKTI SDN. BHD.

31 SPM Model Test Answers Chapter Form 4 13 Chapter Form 5 13 3 1 (i) Use the information in Table 2 to determine the empirical formula of the organic compound. HOTS Analysing Element Carbon, C Hydrogen, H Nitrogen, N Mass (g) 28.57 4.76 66.67 Number of moles 28.57 12 = 2.38 4.76 1 = 4.76 66.67 14 = 4.76 Simplest mole ratio 2.38 2.38 = 1 4.76 2.38 = 2 4.76 2.38 = 2 The empirical formula is CH2 N2 [3 marks] (ii) Given the relative molecular mass of the organic compound is 126. Find the molecular formula of the organic compound. Assume the molecular formula = (Empirical formula)n = (CH2 N2 )n Relative molecular mass = 126 n [12 + (2 × 1) + (2 × 14)] = 126  n = 3 Molecular formula = (CH2 N2 )3 = C3 H6 N6 [2 marks] (c) Based on your answer in 3(b)(ii), what can you say about one molecule of the organic compound? One molecule of the organic compound contains 3 carbon atoms, 6 hydrogen atoms and 6 nitrogen atoms. [1 mark] 3 (b) (i) By assuming the total mass of the compound is 100 g, we can assume that the percentage is equal to the mass of the compound. (ii) Molecular formula = (Empirical formula)n , where n = integer (c) Molecular formula shows the actual number of atoms in a molecule of the substance. Exam Tips F4 Q&A Chemi 3(22-39).indd 31 11/1/2023 5:15:29 PM PENERBIT ILMU BAKTI SDN. BHD.

32 SPM Model Test Answers Chapter Form 4 Chapter Form 5 13 3 1 4 Diagram 2 shows the apparatus set-up to determine the empirical formula of copper(II) oxide. Hydrogen gas is fl owed across hot copper(II) oxide powder until no change is observed. Ethanol Glass tube Wooden block Rubber tube Hole Glass tube Water Copper(II) oxide powder Substance G Hydrochloric acid Glass tube Diagram 2 Table 3 shows the results of the experiment. Description Mass (g) Mass of empty glass tube 8.093 Mass of glass tube + copper(II) oxide powder before heating 9.053 Mass of glass tube + copper(II) oxide powder after heating 8.861 Table 3 (a) (i) Hydrogen gas is produced from the reaction between hydrochloric acid and substance G. Suggest substance G. Zinc [1 mark] (ii) State the observation of copper(II) oxide powder during the heating process. The black powder of copper(II) oxide turns brown. [1 mark] Common Error Candidates do not know how to describe an observation. An observation is a physical change that is seen during the experiment. F4 Q&A Chemi 3(22-39).indd 32 11/1/2023 5:15:29 PM PENERBIT ILMU BAKTI SDN. BHD.

33 SPM Model Test Answers Chapter Form 4 13 Chapter Form 5 13 3 1 (b) Based on the information in Table 3, fi nd the empirical formula of copper(II) oxide. HOTS Analysing Element Cu O Mass (g) 8.861 – 8.093 = 0.768 g 9.053 – 8.861 = 0.192 g Number of moles 0.768 64 = 0.012 0.192 16 = 0.012 Simplest mole ratio 0.012 0.012 = 1 0.012 0.012 = 1 The empirical formula is CuO [4 marks] Common Error Candidates give the mole ratio in decimal form. The simplest mole ratio must be an integer. Divide the number of moles by the smallest number of moles to get the correct ratio. (c) Based on your answer in 4(b), write a balanced chemical equation for the reaction between copper(II) oxide and hydrogen gas. CuO + H2 → Cu + H2 O [2 marks] (d) Can we determine the empirical formula of magnesium oxide using this method? Briefly explain your answer. HOTS Applying No, because magnesium is more reactive than hydrogen. Therefore, hydrogen cannot react with magnesium oxide. [2 marks] 4 (a) (i) Hydrogen is produced when a reactive metal such as zinc or magnesium is reacted with dilute hydrochloric acid. (b) The compound is copper(II) oxide. The elements in this compound are Cu and O. Find the simplest mole ratio of the elements in the compound. (c) In the reaction, copper(II) oxide is reduced by hydrogen into copper and water. (d) This method is only suitable to determine the empirical formula of metal oxide for metals that are less reactive than hydrogen (metals that are located below hydrogen in the reactivity series of metals). Exam Tips F4 Q&A Chemi 3(22-39).indd 33 11/1/2023 5:15:29 PM PENERBIT ILMU BAKTI SDN. BHD.

34 SPM Model Test Answers Chapter Form 4 Chapter Form 5 13 3 1 5 Diagram 3 shows the reaction between copper(II) oxide powder and dilute hydrochloric acid. 3.20 g of copper(II) oxide 2.19 g of hydrochloric acid Diagram 3 The reaction produces copper(II) chloride and water. [Relative atomic mass: H = 1, O = 16, Cl = 35.5, Cu = 64] (a) Write a balanced chemical equation for the reaction. CuO + 2HCl → CuCl2 + H2 O [2 marks] (b) Based on the information given in Diagram 3, (i) calculate the number of moles of copper(II) oxide and hydrochloric acid used in the reaction. RFM of CuO = 64 + 16 = 80 RMM of HCl = 1 + 35.5 = 36.5 Number of moles of CuO = 3.20 80 = 0.04 mol Number of moles of HCl = 2.19 36.5 = 0.06 mol [2 marks] (ii) determine the limiting reactant in the reaction. Hydrochloric acid [1 mark] (c) Based on your answers in 5(b), calculate the mass of (i) excess reactant left in the beaker. From the equation, 2 moles of HCl react with 1 mole of CuO.  0.06 mole of HCl reacts with 0.03 mole of CuO. Mass of CuO reacted = 0.03 × 80 = 2.40 g  Mass of CuO left = 3.20 g – 2.40 g = 0.80 g [3 marks] (ii) copper(II) chloride produced. From the equation, 2 moles of HCl produce 1 mole of CuCl2 .  0.06 mole of HCl produces 0.03 mole of CuCl2 . RFM of CuCl2 = 64 + 2(35.5) = 135  Mass of CuCl2 = 0.03 × 135 = 4.05 g [2 marks] F4 Q&A Chemi 3(22-39).indd 34 11/1/2023 5:15:30 PM PENERBIT ILMU BAKTI SDN. BHD.

147 SPM Model Test Answers Chapter Form 4 13 Chapter Form 5 13 2 1 1 Which of the following defi nes reduction? A Gain of oxygen B Gain of electron C Loss of hydrogen D Increase in oxidation number Answer: B Reduction is defined as: • loss of oxygen • gain of electron • gain of hydrogen • decrease in oxidation number 2 The following shows an ionic equation. X + Y2+ → X2+ + Y Which of the following is true? A X is oxidised B X2+ is oxidised C Y2+ donated electrons D Y2+ is the reducing agent Answer: A Oxidation number of X changes from 0 to +2. Oxidation occurs in X. Oxidation number of Y changes from +2 to 0. Reduction occurs in Y2+. 3 The following chemical reaction shows the reaction between ammonia and copper(II) oxide. Paper 1 Objective Questions 2NH3 (g) + 3CuO(s) → N2 (g) + 3Cu(s) + 3H2 O(l) Which of the following substances is the oxidising agent? A NH3 C N2 B CuO D Cu Answer: B CuO loses oxygen. CuO is reduced. Oxidising agents undergo reduction. 4 The following chemical equation shows a redox reaction. Zn(s) + 2HCl(aq) → ZnCl2 (aq) + H2 (g) What is the change in the oxidation number of hydrogen? A 0 → –1 C +1 → 0 B 0 → +1 D –1 → +1 Answer: C Hydrogen is a Group 1 element. The oxidation number of the element in a compound is +1. The oxidation number of H in hydrogen gas is 0. 5 The following half equation shows a redox reaction. Pb(s) + 2Ag+ (aq) → � Pb2+(aq) + 2Ag(s) 1.1 Oxidation and Reduction Textbook Pages: 4 – 58 Theme 1: Chemical Process Redox Equilibrium 1 CHAPTER F5 Q&A Chemi 1(147-162).indd 147 11/1/2023 5:27:58 PM PENERBIT ILMU BAKTI SDN. BHD.

148 SPM Model Test Answers Chapter Form 4 Chapter Form 5 13 2 1 Which of the following is the correct changes in the oxidation number of lead and silver? Lead, Pb Silver, Ag A +2 → 0 0 → –2 B 0 → +2 +1 → 0 C 0 → +2 +1 → 2 D +2 → 0 0 → –2 Answer: B The oxidation number of an element is zero. The oxidation number of an ion is equal to the charge of the ion. 6 Which of the following shows the correct oxidation number of oxygen in the compounds? H2O2 S2O3 2– A –2 –2 B –2 –1 C –1 –2 D –1 –1 Answer: C The oxidation number of oxygen in a compound is normally –2, except in peroxide, the oxidation number of oxygen is –1. The oxidation number of oxygen in H2O2, 2(+1) + 2x = 0 2x = –2 x = –1 7 Diagram 1 shows the apparatus set-up to investigate the displacement reaction of copper(II) sulphate solution by metal X. The colour of copper(II) sulphate solution turns colourless. Copper(II) sulphate solution Metal X Diagram 1 Which of the following is metal X? HOTS Applying A Pt C Ag B Zn D Au Answer: B Zinc is more electropositive metal than copper in the electrochemical series. Zinc is a reducing agent and displaces copper from copper(II) sulphate solution. 8 What is the oxidation number of chlorine in the following molecules and ions? HOTS Analysing ClO– ClO3 – Cl2O7 A +1 –5 +7 B +1 +5 –7 C +1 +5 +7 D +1 –5 +7 Answer: C The oxidation number of Cl in ClO–, x + (–2) = –1 x = +1 The oxidation number of Cl in ClO3 –, x + 3(–2) = –1 x = +5 The oxidation number of Cl in Cl2O7 , 2x + 7(–2) = 0 2x = +14 x = +7 F5 Q&A Chemi 1(147-162).indd 148 11/1/2023 5:27:58 PM PENERBIT ILMU BAKTI SDN. BHD.

149 SPM Model Test Answers Chapter Form 4 13 Chapter Form 5 13 2 1 9 Which of the following substances converts Fe2+ ions to Fe3+ ions? A Acidifi ed potassium dichromate(VI) solution B Sulphur dioxide gas C Iron(III) chloride D Magnesium Answer: A Conversion of Fe2+ ions to Fe3+ ions is an oxidation reaction. Oxidising agent such as chlorine water, acidified potassium dichromate(VI) solution, acidified potassium manganate(VII) solution, hydrogen peroxide and concentrated nitric acid is required. 10 The manufacturing of sulphuric acid through the Contact Process, involves the following steps. S → SO2 → SO3 → H2 SO4 Which of the following shows the correct sequence of changes in oxidation number of sulphur? A 0 → +2 → +3 → +4 B 0 → +2 → +6 → +6 C 0 → +4 → +6 → +6 D 0 → +4 → +6 → +8 Answers: C The oxidation number of S = 0 (neutral element) The oxidation number of S in SO2, x + 2(–2) = 0 x = +4 The oxidation number of S in SO3, x + 3(–2) = 0 x = +6 The oxidation number of S in H2 SO4 , 2(+1) + x + 4(–2) = 0 x = +6 11 The following equation shows the reaction between carbon and zinc oxide. C + 2ZnO → CO2 + 2Zn Which of the following statements is correct about the reaction? A Zinc oxide is oxidised to zinc B Carbon is the reducing agent C The oxidation number of oxygen increases D The oxidation number of carbon decreases Answer: B Carbon, C changes to CO2 by gaining oxygen through oxidation. 12 Diagram 2 shows the apparatus set-up to study the transfer of electrons. G Electrode X Electrode Y Solution Y Sulphuric acid Solution X Diagram 2 F5 Q&A Chemi 1(147-162).indd 149 11/1/2023 5:27:58 PM PENERBIT ILMU BAKTI SDN. BHD.

150 SPM Model Test Answers Chapter Form 4 Chapter Form 5 13 2 1 If electrode X is the positive terminal, which of the following are solution X and solution Y? Solution X Solution Y A Potassium iodide solution Chlorine water B Iron(II) sulphate solution Acidifi ed potassium manganate(VII) solution C Acidifi ed potassium manganate(VII) solution Potassium iodide solution D Iron(III) sulphate solution Acidifi ed potassium dichromate(VI) solution Answer: C Reduction occurs at electrode X and oxidation occurs at electrode Y. Acidified potassium manganate(VII) solution is an oxidising agent. Potassium iodide solution is a reducing agent. Based on the information, which statement is true? A The powder of metal R can displace metal Q from its salt solution B Metal R oxide is an oxidising agent C Metal Q is an oxidising agent D Metal Q gains electron Answer: B Metal Q is more electropositive than metal R in the ECS. In the redox reaction, metal Q gains oxygen and loses electron. Metal Q is a reducing agent. Metal R oxide loses oxygen and gains electron. Metal R is an oxidising agent. 15 A redox reaction is represented by the following equation. Y2 (aq) + 2KBr(aq) → � 2KY(aq) + Br2 (aq) Element Y is in Group 17 in the Periodic Table of Elements. 13 Gas Y is passed through acidifi ed potassium dichromate(VI), K2 Cr2 O7 solution. The colour of the solution changes from orange to green. What is gas Y? A Chlorine B Sulphur dioxide C Nitrogen dioxide D Hydrogen chloride Answer: B Acidified potassium dichromate(VI) solution is an oxidising agent and reacts with a reducing agent. Chromium(II) ion (orange) is reduced to chromium(III) ion (green). Sulphur dioxide is a reducing agent. 14 The following information are the observations when the powder of metal Q is heated with black metal R oxide. • A glow is seen • The residue produced is yellow when it is hot and white when it is cold F5 Q&A Chemi 1(147-162).indd 150 11/1/2023 5:27:58 PM PENERBIT ILMU BAKTI SDN. BHD.

151 SPM Model Test Answers Chapter Form 4 13 Chapter Form 5 13 2 1 What can be observed if element Y is replaced with iodine? A Brown gas is produced B No change is observed C Colourless solution is produced D Brown colour of iodine is decolourised Answer: B In Group 17, iodine is lower than bromine. The displacement reaction does not occur because iodine is less reactive than bromine. Standard Electrode Potential 1.2 16 Table 1 shows the value of standard electrode potential for some half-cells. Half-cell equation E0 value (V) I 2 (s) + 2e– 2I–(aq) +0.54 Al3+(aq) + 3e– Al(s) –1.66 Pb2+(aq) + 2e– Pb(s) –0.13 Cu2+(aq) + 2e– Cu(s) +0.34 Table 1 Which of the following is the strongest reducing agent? A I 2 B Al C Pb D Cu Answer: B The E0 value of Al is the most negative. Al has a higher tendency to release electrons and undergoes oxidation. 17 The following shows a chemical equation. Fe(s) + CuSO4 (aq) → � FeSO4 (aq) + Cu(s) Which of the following statements is correct about the reaction? HOTS Analysing [Fe2+ + 2e– Fe, E0 = –0.44 V; Cu2+ + 2e– Cu, E0 = +0.34 V] A Iron, Fe is a stronger oxidising agent B Iron, Fe undergoes reduction reaction C The E0 value of iron, Fe is more positive than E0 of copper, Cu D The E0 value of iron, Fe is more negative than E0 of copper, Cu Answer: D Fe is located higher than Cu in the ECS. The series is arranged from the most negative to the most positive standard electrode potential value, E0. 1.3 Voltaic Cell 18 Diagram 3 shows a Daniell cell. V V _ + Copper Porous pot Copper(II) sulphate solution Zinc – + Zinc sulphate solution Diagram 3 What is the E0 cell for the cell? [Zn2+ + 2e– Zn, E0 = –0.76 V; Cu2+ + 2e– Cu, E0 = +0.34 V] A +1.10 V C –0.42 V B +0.42 V D –1.10 V F5 Q&A Chemi 1(147-162).indd 151 11/1/2023 5:27:59 PM PENERBIT ILMU BAKTI SDN. BHD.

152 SPM Model Test Answers Chapter Form 4 Chapter Form 5 13 2 1 Answer: A E0 cell = E0 (cathode) – E0 (anode) = (+0.34) – (–0.76) = +1.10 V 19 Diagram 4 shows a simple chemical cell. V Silver electrode Salt bridge Silver nitrate solution Copper electrode Copper(II) nitrate solution Diagram 4 What is the E0 cell for the cell? [Ag+ + e– Ag, E0 = +0.80 V; Cu2+ + 2e– Cu, E0 = +0.34 V] A –1.14 V B –0.46 V C +0.46 V D +1.14 V Answer: C E0 cell = E0 (cathode) – E0 (anode) = (+0.80) – (+0.34) = +0.46 V 20 The following is a cell notation for a voltaic cell. Zn(s) | Zn2+(aq) || Fe3+(aq), Fe2+(aq) | Pt(s) What is the E0 cell for the voltaic cell? [Zn2+ + 2e– Zn, E0 = –0.76 V; Fe3+ + 2e– Fe2+, E0 = +0.77 V] A +0.01 V B +1.53 V C –0.01 V D –1.53 V Answer: B E0 cell = E0 (cathode) – E0 (anode) = (+0.77) – (–0.76) = +1.53 V 1.4 Electrolytic Cell 21 Diagram 5 shows the apparatus set-up to purify silver by electrolysis. A Cathode Electrolyte Anode Ammeter Battery Diagram 5 F5 Q&A Chemi 1(147-162).indd 152 11/1/2023 5:27:59 PM PENERBIT ILMU BAKTI SDN. BHD.

153 SPM Model Test Answers Chapter Form 4 13 Chapter Form 5 13 2 1 Which of the following is correct? Cathode Anode Electrolyte A Pure silver Impure silver Silver chloride B Pure silver Impure silver Silver nitrate C Impure silver Pure silver Nitric acid D Carbon Pure silver Silver nitrate Answer: B Cathode: Pure electrode Electrolyte: Aqueous salt solution of silver Anode: Impure electrode 22 Diagram 6 shows the apparatus set-up for the purifi cation of copper. Copper(II) sulphate solution Impure copper Pure copper Diagram 6 Which of the following statements is true? A Impure copper electrode becomes thicker B Pure copper electrode becomes thinner C Half equation at the impure copper electrode is Cu → Cu2+ + 2e– D Reduction occurs at the anode Answer: C During purification, anode (impure copper) becomes thinner and cathode (pure copper) becomes thicker. Oxidation half equation at the anode: Cu → Cu2+ + 2e– Reduction half equation at the cathode: Cu2+ + 2e– → Cu 23 Diagram 7 shows the apparatus set-up used to coat an iron bracelet with silver. A Silver electrode Iron bracelet Silver nitrate solution Diagram 7 Which of the following statements are true? I Silver electrode is the anode II A thin layer of silver is formed on the bracelet III Iron bracelet is the anode IV Silver chloride can be used to replace silver nitrate solution as electrolyte A I and II C II and IV B I and III D III and IV Answer: A Oxidation half equation at the anode: Ag → Ag+ + e– Reduction half equation at the cathode: Ag+ + e– → Ag Silver chloride is insoluble in water. F5 Q&A Chemi 1(147-162).indd 153 11/1/2023 5:27:59 PM PENERBIT ILMU BAKTI SDN. BHD.

154 SPM Model Test Answers Chapter Form 4 Chapter Form 5 13 2 1 Extraction of Metal from Its Ore 1.5 24 Diagram 8 shows an aluminium ore found in Malaysia. Diagram 8 Which of the following is the suitable method to extract the metal from its ore? A Electrolysis B Combustion C Reduction by carbon D Fractional distillation Answer: A Aluminium is more reactive than carbon. 25 In the extraction of aluminium from its ore, cryolite, Na3 AlF6 is added into the aluminium oxide, Al2 O3 during the process. What is the reason of adding cryolite? A To increase the melting point of aluminium B To increase the amount of electricity used C To decrease the production of carbon dioxide D To lower the melting point of aluminium oxide Answer: D The melting point of aluminium oxide is 2 000 °C. Cryolite is added to lower the melting point. When the melting point decreases, the electrical energy used is reduced. There is no effect on the production of carbon dioxide. 1.6 Rusting 26 Diagram 9 shows the rusting mechanism on iron door. O2 O2 Anode Cathode Water Rust Iron Diagram 9 Which of the following half equations occur at the negative terminal and positive terminal? Negative terminal Positive terminal A Fe2+ → Fe3+ + 2e– O2 + 2H2 O + 4e– → 4OH– B 2H+ + 2e– → H2 Fe → Fe2+ + 2e– C O2 + 2H2 O + 4e– → 4OH– Fe2+ → Fe3+ + 2e– D Fe → Fe2+ + 2e– O2 + 2H2 O + 4e– → 4OH– F5 Q&A Chemi 1(147-162).indd 154 11/1/2023 5:28:00 PM PENERBIT ILMU BAKTI SDN. BHD.

155 SPM Model Test Answers Chapter Form 4 13 Chapter Form 5 13 2 1 Answer: D Oxidation occurs at the anode (negative terminal). Reduction occurs at the cathode (positive terminal). 27 Which of the following methods are used to prevent rusting? I Electrolysis II Galvanisation III Burning IV Sacrifi cial protection metals A I and II B I and III C II and IV D III and IV Paper 2 Section A – Structured Questions 1 Diagram 1 shows the apparatus set-up for a reaction involving transfer of electrons at a distance between iron(II) sulphate solution and acidifi ed potassium manganate(VII) solution. G Carbon electrode X Acidifi ed potassium manganate(VII) solution Sulphuric acid Iron(II) sulphate solution Carbon electrode Y Diagram 1 (a) State the colour change in the the solution at electrode X. Purple colour changes to colourless [1 mark] Common Error Candidates did not describe the changes clearly. Candidates must describe the changes (from______ colour to ______ colour) (b) State the change in the oxidation number of manganese, Mn. +7 to +2 [1 mark] F5 Q&A Chemi 1(147-162).indd 155 11/1/2023 5:28:00 PM PENERBIT ILMU BAKTI SDN. BHD.

156 SPM Model Test Answers Chapter Form 4 Chapter Form 5 13 2 1 (c) Draw arrows in Diagram 1 to show the direction of electron flow. HOTS Analysing G Carbon electrode X e– e– Acidifi ed potassium manganate(VII) solution Sulphuric acid Iron(II) sulphate solution Carbon electrode Y [1 mark] (d) A brown solution is formed at electrode Y. (i) What is the ion presents in the solution? Iron(III) ion/Fe3+ [1 mark] (ii) Describe a chemical test to verify the presence of the ion stated in 1(d)(i). HOTS Analysing Add a few drops of sodium hydroxide, NaOH solution into the sample solution. A brown precipitate is formed to confirm the presence of iron(III) ions, Fe3+. [1 mark] (e) Write the half equation of the reaction that occurs at (i) electrode X: MnO4 – + 8H+ + 5e– → Mn2+ + 4H2 O [1 mark] (ii) electrode Y: Fe2+ → Fe3+ + e– [1 mark] (f) Write the overall ionic equation of this reaction. 5Fe2+ + MnO4 – + 8H+ → 5Fe3+ + Mn2+ + 4H2 O [1 mark] (g) Name another reagent that can be used to replace acidified potassium manganate(VII) solution. Acidified potassium dichromate(VI) solution [1 mark] F5 Q&A Chemi 1(147-162).indd 156 11/1/2023 5:28:00 PM PENERBIT ILMU BAKTI SDN. BHD.

157 SPM Model Test Answers Chapter Form 4 13 Chapter Form 5 13 2 1 1 (b) Half equation of reduction: MnO4 – + 8H+ + 5e– → Mn2+ + 4H2 O x + 4(–2) = –1 x = +2 x = –1 + 8 x = +7 (c) Electrons fl ow from negative terminal to positive terminal. (d) (i) Iron(III) ion, Fe3+ is brown. Iron(II) ion, Fe2+ is green. (ii) Aqueous NH3 can also be used to test the presence of Fe3+ ion. A brown precipitate will be formed. (g) Step 1: Write the half equations and balance the number of electrons: MnO4 – + 8H+ + 5e– → Mn2+ + 4H2 O . . . 1 � Fe2+ → Fe3+ + e– . . . 2 × 5 Step 2: Sum up the balanced equations: MnO4 – + 8H+ + 5e– → Mn2+ + 4H2 O 5Fe2+ → 5Fe3+ + 5e– 5Fe2+ + MnO4 – + 8H+ → 5Fe3+ + Mn2+ + 4H2 O (Overall ionic equation) Exam Tips 2 Diagram 2 shows the apparatus set-up for an experiment to investigate the reactions that occur in test tubes P and Q after 3 days. Argentum nitrate solution Copper wire Iron wire Test tube P Test tube Q Diagram 2 (a) State the observation in test tubes P and Q. Test tube P: The colourless solution turns blue Test tube Q: The colourless solution turns green [2 marks] (b) Write the half equation for the reaction in test tubes P and Q. Test tube P: Cu → Cu2+ + 2e– Test tube Q: Fe → Fe2+ + 2e– [2 marks] F5 Q&A Chemi 1(147-162).indd 157 11/1/2023 5:28:00 PM PENERBIT ILMU BAKTI SDN. BHD.

158 SPM Model Test Answers Chapter Form 4 Chapter Form 5 13 2 1 (c) Describe briefly a chemical test to identify the cation formed in 2(b). Test tube P: Add a few drops of NaOH solution to the solution. Dark blue solution is obtained. Test tube Q: Add a few drops of NaOH solution to the solution. Green solution is obtained. [2 marks] (d) Which metal, copper or iron can undergo corrosion easily based on the observation? Explain why. HOTS Evaluating Iron metal undergoes corrosion easier than copper metal. Iron metal is oxidised when the iron atom releases electrons to form iron(II) ions, Fe2+. [2 marks] 2 (d) Fe is more electropositive than Cu. Fe rusts faster than Cu. Exam Tips Paper 2 Section B & C – Essay Questions 3 (a) Diagram 3 shows a simple chemical cell. V Silver Silver nitrate solution Copper Diagram 3 (i) Describe briefly how the above cell works. Include in your description, the related half equations and observations. [The standard electrode potential: Cu2+(aq) + 2e– Cu(s), E0 = +0.34 V; Ag+ (aq) + e– Ag(s), E0 = +0.80 V] [10 marks] (ii) Table 1 shows the information about another two chemical cells. Cell Pair of metal Cell voltage (V) Negative terminal I Zinc and copper 1.10 Zinc II Zinc and silver 1.56 Zinc Table 1 Use the information in Table 1 to calculate the voltage of the cell shown in Diagram 3. [2 marks] F5 Q&A Chemi 1(147-162).indd 158 11/1/2023 5:28:00 PM PENERBIT ILMU BAKTI SDN. BHD.

159 SPM Model Test Answers Chapter Form 4 13 Chapter Form 5 13 2 1 (b) You are given the necessary chemicals and apparatus below. Aluminium plate, copper plate, salt bridge, voltmeter, beakers, connecting wires, crocodile clips (i) Name two suitable electrolytes that can be used to set up the apparatus. [2 marks] (ii) Draw a labelled diagram of a voltaic cell used to convert chemical energy to electrical energy. HOTS Analysing Show the movement of electrons in your diagram. [6 marks] Answers 3 (a) (i) – Copper is more electropositive than silver. The E0 value of Cu is more negative than E0 of Ag. � – Copper electrode acts as negative terminal, while silver electrode acts as positive terminal. � – Electrons move from negative terminal to positive terminal through the external circuit. � – Oxidation half equation at negative terminal (anode): Cu → Cu2+ + 2e– � – Observation: Copper electrode becomes thinner. � – Reduction half equation at positive terminal (cathode): Ag+ + e– → Ag � – Observation: Shiny solid deposited at silver electrode/Silver electrode becomes thicker/Intensity of blue solution increases � – Overall ionic equation: Cu + 2Ag+ → Cu2+ + 2Ag � – The fl ow of electrons causes the defl ection of voltmeter needle and register a reading. � – E0 cell = E0 (cathode) – E0 (anode) = +0.80 V – (+0.34 V) = +0.46 V Common Error Candidates must compare between the metals in terms of their tendency to release electrons. Then, the negative and positive terminals can be determined. (ii) 1.56 V 1.10 V Zn Cu Ag For copper–silver cell, Cell voltage = 1.56 V – 1.10 V = 0.46 V F5 Q&A Chemi 1(147-162).indd 159 11/1/2023 5:28:01 PM PENERBIT ILMU BAKTI SDN. BHD.

160 SPM Model Test Answers Chapter Form 4 Chapter Form 5 13 2 1 (b) (i) Aluminium nitrate solution, copper(II) nitrate solution (ii) 3 (a) (ii) Arrange the metals according to their electropositivity. (b) (i) Choose the electrolytes based on the electrodes and it must be soluble in water. Aluminium plate – Aluminium nitrate (soluble in water and it is the salt solution of aluminium) Copper plate – Copper(II) nitrate (soluble in water and it is the salt solution of copper) (ii) Candidates must be able to draw a functional voltaic cell diagram. • Electrodes must be immersed in the solutions • Salt bridge must be immersed in the solutions • Dashed lines must be drawn to represent solution Exam Tips 4 (a) Table 2 shows the list of apparatus and materials for an experiment. Apparatus Materials Zinc plate Silver plate Porous pot Connecting wire Voltmeter Beaker Zinc nitrate solution Silver nitrate solution Table 2 A student wants to conduct an experiment to study the purifi cation of silver. Power supply is not provided. Therefore, the student must build a chemical cell using the apparatus and materials provided in Table 2 to obtain electric current. (i) Draw the apparatus set-up that represents the power supply in the experiment. HOTS Creating [2 marks] V + _ V _ + Aluminium plate Aluminium nitrate solution Copper(II) nitrate solution Copper plate e– e– Salt bridge Voltmeter F5 Q&A Chemi 1(147-162).indd 160 11/1/2023 5:28:01 PM PENERBIT ILMU BAKTI SDN. BHD.