WJEC GCSE Chemistry Practice Exam

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• What is the general formula for alkanes, and are they saturated?
• Why is energy efficiency important in chemical manufacturing?
• Which physical process is used to identify what substances are present in a mixture by separating components?
• In a precipitation reaction, what forms and separates from the solution?
• What is a salt bridge and what is its function in a galvanic cell?
• To determine the empirical formula from percentage composition, which sequence is correct?
• Which statement correctly describes the differences between an element, a compound, and a mixture, and gives a typical example for each?
• Which of the following is an alloy?
• How do you work out the number of neutrons?
• What gas is produced when carbonate ions react with acid?
• Which particle is found in the nucleus with no electric charge?
• What is the basic premise of the collision theory?
• Which statement best describes condensation polymerisation?
• Which group do alkali metals belong to in the periodic table?
• Which layer lies between the mantle and the inner core?
• Which boundary type is characterized by plates sliding past each other with no crust formation or destruction?
• How do you calculate a theoretical yield in a chemical reaction from a balanced equation?
• The capacity of certain gases in the atmosphere to trap heat, thereby warming the Earth, is called the
• How can you test for carbonate ions in a sample?
• Which subatomic particle has a negative electric charge and a relatively small mass compared with protons and neutrons?
• In the carbonate test, what observation indicates a positive result?
• Which subatomic particle has a positive electric charge?
• During the electrolysis of brine, which gas is produced at the anode?
• Which term refers to a graph indicating the solubility of a solute at different temperatures?
• What is the term for the general condition of water determined by dissolved minerals and ions such as calcium and magnesium?
• Isotopes have the same chemical properties but differ in physical properties because they differ in…
• Which statement about ionic compounds is true?
• How can you determine the rate of a reaction from a concentration-time graph?
• Why is energy to break bonds and energy released on forming bonds described as they are?
• Which process separates liquids based on boiling points and includes condensation of the vapor?
• What is a catalyst and how does it affect a reaction?
• What is a substance composed of only one type of atom and cannot be broken down by chemical reactions?
• Which statement about the outer electrons of alkali metals is true?
• What is Avogadro's constant and how is it used in GCSE calculations?
• Which reaction involves one element replacing a similar element in a compound?
• In a displacement reaction, a more reactive element replaces a less reactive element in a compound.
• What happens to the melting and boiling points of alkali metals as you move down the group?
• Which particle is outside the nucleus and orbits the nucleus?
• How would you demonstrate the conservation of mass in a reaction in a closed system?
• Which layer lies directly beneath the Earth's crust?
• Isotopes are atoms of the same element that have different numbers of neutrons.
• Which type of water hardness is caused by chloride and sulfate salts of calcium and magnesium and is not removed by boiling or filtering?
• Which gas is the most abundant in Earth's atmosphere?
• What is the percentage by mass of chlorine in sodium chloride (NaCl)?
• Which boundary occurs when plates move away from each other?
• Which type of water hardness is caused by calcium carbonate and magnesium bicarbonate and can be removed by boiling then filtering?
• Where are protons, neutrons, and electrons located, and what are their charges?
• To determine empirical formula from percent composition, which data is essential?
• The vertical arrangement of elements in the periodic table is called?
• How do alkenes differ from alkanes in terms of bonding and reactivity?
• Using universal indicator, what does pH 3 indicate?
• During respiration, what happens to oxygen and carbon dioxide?
• What is the correct sequence to obtain a pure dry salt from a soluble salt?
• Which term refers to the supercontinent that existed about 225 million years ago?
• Water hardness is caused by dissolved calcium and magnesium ions; temporary hardness from hydrogencarbonates can be removed by boiling. Which option best reflects this statement?
• In a calorimetry experiment, if 418 J are recorded for a measurement rather than the correct value, which option shows the correct heat transfer for a 100 g water sample warming by 2°C?
• What term describes rain that contains more acid than normal?
• A compound that consists of positive and negative ions is called what?
• During esterification, what is the role of an acid catalyst?
• How would you test for chloride, sulfate, and carbonate ions in a solution?
• What is the change of a substance from a liquid to a gas called?
• Which layer lies between the crust and the outer core?
• Which of the following is an element?
• What is the charge of a proton?
• Which term tells the type and number of atoms in a substance?
• Which test is used to identify sulfate ions in solution?
• What does atom economy mean, and why is it important?
• What does the theoretical yield assume in a chemical calculation?
• Which statement best describes the difference between a polymer and a small molecule covalent compound?
• How many electrons are in the outermost shell of alkali metals?
• Which boundary occurs when plates move toward each other?
• What are atoms of the same element that have different numbers of neutrons called?
• Which particle has a negative charge and is much lighter than protons and neutrons?
• Which statement about the outer electrons of alkali metals is true?
• The outer core is composed mainly of which two elements?
• In a flame test, which color is produced by potassium?
• What are the main practical skills assessed in WJEC GCSE Chemistry, and why are practicing them important?
• What is the relative formula mass of CH4?
• What term describes very unreactive elements in the periodic table?
• What is the mass number of an atom with 3 protons and 4 neutrons?
• Esters are commonly used in which areas?
• Which type of reaction forms an insoluble substance that separates from the solution?
• Which item would be categorized as an industrial pollutant when assessing water quality?
• In an exothermic reaction, how does the energy of products compare to the energy of reactants?
• How does increasing the surface area of a solid reactant influence the rate of a reaction?
• Which statement correctly describes activation energy?
• Which term best describes a method that reduces the amount of water we use?
• Which particle has a positive electric charge and a mass around 1 amu?
• Which of the following describes how concentration affects the rate of a reaction?
• How does decreasing particle size affect the rate of a reaction between a solid and a liquid?
• Which plate boundary is defined as two plates moving toward each other?
• When can carbon reduce a metal oxide to the metal?
• Which particle is outside the nucleus and primarily involved in chemical reactions?
• Which two functional groups are commonly found in organic molecules, with an alcohol as an example for one and a carboxyl group as an example for the other?
• Approximately what percentage of Earth's atmosphere is oxygen?
• Which process separates materials based on particle size?
• Which process purifies a liquid by heating and then cooling it?
• Which term describes the addition of fluoride to drinking water to prevent tooth decay?
• What term describes substances that cannot be broken down by chemical means?
• What is an ion and how does ionic bonding form compounds?
• Which property is the same for elements within the same group?
• Why are ionic compounds typically solid at room temperature?
• Which test is used to identify metal cations by the color produced in a flame?
• According to collision theory, which statement correctly describes the effect of temperature on the rate of a reaction?
• How are nitrogen oxides formed in the atmosphere?
• What is an alloy?
• Why do ionic compounds conduct electricity when melted or dissolved but not as a solid?
• Which layer surrounds the inner core and is molten iron and nickel?
• What is the primary purpose of using inhibitors as corrosion prevention?
• What is the purpose of desulfurizing fuels?
• What is the pH of a neutral solution?
• The outermost solid layer of the Earth is known as the
• In chromatography, how does the Rf value relate to movement?
• What is the electronic configuration of oxygen (atomic number 8)?
• Define relative atomic mass (Ar) and relative formula mass (Mr). How are they used?
• Why do metals have high melting and boiling points?
• What is the mass number of an atom with 6 protons and 6 neutrons?
• Which type of reaction do alkenes readily undergo due to the C=C bond?
• Which part of Earth is a dense sphere at the center made of iron and nickel?
• A reaction has a theoretical yield of 50 g and an actual yield of 30 g. Calculate the percentage yield.
• What is the test for ammonium ions?
• How is crude oil separated into fractions?
• What term describes the measure of how much solute can dissolve in a given solvent at a given temperature?
• What is the greenhouse effect?
• Which pollutants contribute to acid rain and what are their sources?
• Which statement best defines rate of reaction?
• Which of the following is not a pure substance?
• In collision theory, which statement describes the conditions for a collision to lead to a reaction?
• What is the greenhouse effect and why is it a concern for the environment?
• Which subatomic particle has a mass approximately 1 atomic unit and a positive electric charge?
• Which subatomic particle has a negative electric charge?
• What is electrolysing brine (concentrated NaCl solution) and what products are formed at the electrodes?
• In an exothermic reaction, how does the energy of the products compare to the energy of the reactants?
• What happens if activation energy is lowered?
• The molecular formula CH4 has a relative formula mass of 16. If the mass of carbon is 12, what is the mass contributed by hydrogen in CH4?
• What is the process of removing salt from ocean water called?
• How can metal corrosion be prevented by protective coatings and galvanising?
• What is addition polymerization?
• Which statement best describes a simple formula?
• In a balanced chemical equation, what is conserved?
• Which statement about catalysts and enthalpy is true?
• Fractional distillation separates crude oil into fractions primarily because of differences in what property?
• What is the percentage yield and how do you calculate it?
• What is the term for the arrangement of elements in columns with repeating properties?
• What is the effect of a catalyst on a reaction?
• What causes acid rain, and what are its environmental impacts?
• How many moles are in 24 g of CO2? The relative formula mass is 44.
• Which particle has a very small mass compared with protons and neutrons?
• Which subatomic particle has a mass of about 1 atomic mass unit and no electric charge?
• Which statement about rust formation is true?
• Which statement correctly describes enthalpy change and how it can be measured in a calorimeter?
• In a flame test, which color is produced by lithium?
• Which statement about the outer electrons of alkali metals is true?
• How does a catalyst affect the energy profile of a reaction?
• Which particle is neutral and has a mass close to that of a proton?
• In chromatography, why do substances travel different distances?
• Why is recycling metals beneficial for energy use and the environment?
• Which layer of the Earth's interior is described as semi-liquid?
• Which particle carries a positive charge and is found in the atomic nucleus?
• How can air pollution be reduced?
• Which statement defines a covalent bond?
• Differentiate between addition polymerisation and condensation polymerisation and give an example of each.
• Why are metals able to conduct electricity in solid form?
• What distinguishes isotopes of the same element?
• How do you calculate the Mr of NaCl?
• Which statement about infrared radiation and greenhouse gases best describes their effect?
• Which statement correctly describes natural water?
• Which statement lists the three main ideas of the particle model of matter used in GCSE Chemistry?
• How does increasing concentration affect the rate of a reaction?
• Which list contains the three particles found in an atom?
• What term describes a substance made up of atoms of two or more different elements joined by chemical bonds?
• What is the effect of higher temperature on reaction rate?
• What is activation energy and how does temperature influence the rate of a reaction?
• Which statement correctly describes Arrhenius acids and bases?
• If 5000 J of heat is released for 0.02 moles of reactant, what is the energy change per mole?
• In a flame test for potassium, which color is observed?
• What distinguishes galvanic and electrolytic cells?
• Which statement generally describes covalent molecular substances compared with ionic compounds?
• What pollutant are catalytic converters primarily used to reduce in vehicle exhaust?
• Which statement best describes relative atomic mass (Ar)?
• In the reaction 2H2 + O2 -> 2H2O, if 2 moles of O2 react, how many moles of H2O are produced?
• Which statement best describes exothermic and endothermic reactions?
• Why are elements in the same group chemically similar?
• In a closed system, which statement about mass is true?
• What is an ore and what processes remove useful metals from ores?
• Which layer forms the outermost solid shell of the Earth?
• Which statement best defines atom economy?
• What is chromatography used for?
• Distinguish between a pure covalent bond and a polar covalent bond.
• Halogens belong to which group?
• What is a key reason for the high reactivity of alkali metals with water?
• In a flame test, which color is produced by sodium?
• Which technique separates substances based on movement through a medium and interactions with stationary and mobile phases?
• What is the charge of an electron?
• In a calorimetry experiment, which expression correctly describes the energy change for the water and how to obtain per-mole value?
• In isotopic notation, what do A and Z represent?
• Which process uses a porous barrier to separate a solid from a liquid?
• Which trend describes the reactivity of Group 1 elements as you go down the group?
• What is rust and how can corrosion be prevented?
• Which test confirms the presence of carbonate ions in solution?
• What term describes a grouping of two or more substances that do not chemically combine?
• What are the major components of the modern atmosphere and how have human activities altered levels of CO2?
• What are the main components of Earth's atmosphere?
• How do you work out the mass number of an atom?
• Which quantity tells us the number of protons in the nucleus?
• Which statement pairs a property of ionic compounds with a property of covalent molecules?
• What is true about catalysts?
• Write the balanced equation for the complete combustion of propane.
• How are esters formed and what is a typical use for esters?
• What is the charge of a neutron?
• What properties result from a giant covalent structure like diamond?
• Which gas is most abundant in Earth's atmosphere?
• What does the period number indicate?
• What is the process by which one ion is displaced by another called?
• In water treatment, which process is defined as the exchange of ions where one ion is displaced by another?
• What is the chemical formula of a molecular compound called?
• Which layer lies directly beneath the crust?
• Why is sodium chloride (NaCl) a good example of ionic bonding?
• Which term describes the semi-liquid layer of the Earth's interior composed mainly of iron, silicon, and magnesium?
• The horizontal row on the periodic table is called?
• In a reaction with two reactants, the theoretical yield is determined by which reactant?
• In complete combustion of propane, what are the main gaseous products?
• Which plate boundary is defined as two plates moving away from each other?
• Which statement correctly matches halide ion to silver nitrate precipitate color?
• If the percent yield is 75% and theoretical yield is 40 g, actual yield is?
• What term describes the mass of an atom relative to other atoms?
• In chromatography, what does the retardation factor (Rf) tell you?
• During combustion, what happens to oxygen and carbon dioxide?
• How does halogen reactivity change as you move down Group 7?
• Which boundary is described as where two tectonic plates slide past each other with no crust formed or destroyed?
• Which of the following is NOT a common factor affecting the rate of a chemical reaction?
• Which statement describes how to calculate the Mr of NaCl correctly?
• When a substance is heated, how do particle energy and distance change, and what effect might it have on the state?
• The outer core is primarily in which physical state?
• Which description matches Earth's atmosphere given the composition 21% oxygen, 78% nitrogen, 1% other gases and water vapor?
• What is a balanced equation and why is balancing important?
• Which particle has a mass close to that of a proton and carries no electric charge?
• Which of the following is not a corrosion prevention method?
• In photosynthesis, what happens to oxygen and carbon dioxide?