Introducing chemical reactions: OCR GCSE Combined Science A questions

Every OCR GCSE Combined Science A exam question on C3.1 Introducing chemical reactions, 2018–2025, with its mark scheme and examiner’s report.

All 118 questions on Introducing chemical reactions, as a list

June 2025, Chemistry Paper 3 Foundation, Q2 (1 mark): 24 g of magnesium reacts with oxygen to make 40 g of magnesium oxide. What mass of magnesium oxide is made when 12 g of magnesium reacts? A 20 g B 24 g C 36 g D
June 2025, Chemistry Paper 3 Foundation, Q3 (1 mark): What type of change is shown in the diagram? + Iron Sulfur Iron sulfide A A change of state B A chemical change C A physical change D A reversible change Your a
June 2025, Chemistry Paper 3 Foundation, Q4 (1 mark): The diagram shows a chemical reaction. Balance 162.2 g Why does the mass on the balance decrease during the reaction? A A gas is produced. B A liquid is produce
June 2025, Chemistry Paper 3 Foundation, Q13(d) (3 marks): Sodium chloride contains 39% sodium. Calculate the mass of sodium that is produced from the electrolysis of 160 kg of sodium chloride. Give your answer to 2 sig
June 2025, Chemistry Paper 3 Foundation, Q14(d)(i) (1 mark): This is the equation for the reaction. N2(g) + H2(g) 2NH3(s) What is the missing number that balances the equation? Tick (3) one box. 2 3 4 [1]
June 2025, Chemistry Paper 3 Foundation, Q14(d)(ii) (1 mark): Calculate the relative formula mass, Mr, of ammonia, NH3. Relative atomic masses (Ar): H = 1 N = 14 Relative formula mass of ammonia = [1]
June 2025, Chemistry Paper 3 Foundation, Q14(e) (1 mark): A student thinks that the empirical formula of ammonia is NH3. Explain why the student is correct. Tick (3) one box. Ammonia contains only two elements. Ammonia
June 2025, Chemistry Paper 4 Foundation, Q12(c)(i) (1 mark): Sodium is a solid at room temperature. Complete the equation by writing in the missing state symbol for sodium. [1]
June 2025, Chemistry Paper 4 Foundation, Q16(a) (2 marks): Complete the balanced symbol equation for the reaction. 2H2O2(aq) H2O(l) + (g) [2]
June 2025, Chemistry Paper 9 Higher, Q4 (1 mark): The diagram shows a chemical reaction. Balance 162.2 g During the reaction the mass on the balance decreases. Which state symbol describes the product that caus
June 2025, Chemistry Paper 9 Higher, Q10 (1 mark): How many grams of NaOH are found in 50 cm3 of a 4 g / dm3 solution of NaOH(aq)? A 0.08 g B 0.2 g C 2 g D 80 g Your answer [1] Section B
June 2025, Chemistry Paper 9 Higher, Q12(c)(i) (1 mark): What is the empirical formula of phosphorus trioxide? Tick (✓) one box. PO P2O3 P4O6 [1]
June 2025, Chemistry Paper 9 Higher, Q12(c)(ii) (2 marks): Complete the balanced symbol equation for the reaction of phosphorus trioxide with water. P4O6 + H2O H3PO3 [2]
June 2025, Chemistry Paper 9 Higher, Q15(d)(iii) (4 marks): The calcium hydroxide solution contains 0.038 g of calcium hydroxide. Calculate the maximum mass of carbon dioxide that can react with the calcium hydroxide sol
June 2025, Chemistry Paper 10 Higher, Q11(a) (2 marks): Complete the balanced symbol equation for the reaction. 2H2O2(aq) H2O(l) + (g) [2]
June 2024, Chemistry Paper 3 Foundation, Q1 (1 mark): When iron reacts with dilute hydrochloric acid, bubbles of hydrogen are produced. Which state symbol describes these bubbles? A aq B g C l D s Your answer [1]
June 2024, Chemistry Paper 3 Foundation, Q16(a) (1 mark): Calculate the relative formula mass of one OH. Relative atomic mass (Ar): H = 1.0 O = 16.0 Relative formula mass of one OH = [1]
June 2024, Chemistry Paper 3 Foundation, Q16(b) (2 marks): Use your answer to part (a) to calculate the relative atomic mass of X. Relative atomic mass of X = [2]
June 2024, Chemistry Paper 3 Foundation, Q16(c) (1 mark): Use your answer to part (b) to identify X. Use the Periodic Table on the Data Sheet. [1]
June 2024, Chemistry Paper 3 Foundation, Q17(b) (2 marks): Lithium reacts with oxygen to make lithium oxide. Complete the balanced symbol equation for the reaction. Li + O2 Li2O [2]
June 2024, Chemistry Paper 4 Foundation, Q4 (1 mark): The word equation shows how iron is extracted from iron oxide. iron oxide + carbon iron + carbon dioxide The table shows the masses of the reactants and product
June 2024, Chemistry Paper 4 Foundation, Q16(d) (2 marks): During the purification, aluminium oxide, Al 2O3, is produced from aluminium hydroxide, Al (OH)3. Complete the balanced symbol equation for the reaction. Al (OH
June 2024, Chemistry Paper 9 Higher, Q4 (1 mark): This is the equation for the reaction between copper carbonate and dilute hydrochloric acid: CuCO3(s) + 2HCl(aq) CuCl 2(…) + CO2(g) + H2O(l) What is the state s
June 2024, Chemistry Paper 9 Higher, Q7 (1 mark): The equation shows the reaction of zinc carbonate when it is heated. ZnCO3(s) ZnO(s) + CO2(g) • 5.0 g of zinc carbonate is heated in a test tube for 10 minutes.
June 2024, Chemistry Paper 9 Higher, Q8 (1 mark): Which statement describes the mole? A The mole is defined relative to carbon-14. B The mole is the unit for the amount of a substance. C The number of particles
June 2024, Chemistry Paper 9 Higher, Q10 (1 mark): What is the empirical formula of this compound? Key: = Carbon = Hydrogen = Oxygen A CHO B CH3O C C2H6O2 D HOCH2CH2OH Your answer [1] Section B
June 2024, Chemistry Paper 9 Higher, Q11(b) (2 marks): Lithium reacts with oxygen to make lithium oxide. Complete the balanced symbol equation for the reaction. Li + O2 Li2O [2]
June 2024, Chemistry Paper 9 Higher, Q14(e) (3 marks): A student dissolves 2 g of a strong acid in 250 cm3 of water. Calculate the concentration of the solution formed in g / dm3. Concentration of the solution = g /
June 2024, Chemistry Paper 9 Higher, Q15(a) (1 mark): Explain the effect of a limiting reactant on a reaction. [1]
June 2024, Chemistry Paper 9 Higher, Q15(b) (3 marks): Calculate the number of moles in 2.00 g of copper oxide and 1.00 g of carbon. Give your answers to 3 decimal places. Relative atomic mass (Ar): C = 12.0 O = 16.
June 2024, Chemistry Paper 9 Higher, Q15(c) (1 mark): Use your answers in part (b) to explain why copper oxide is the limiting reactant. [1]
June 2024, Chemistry Paper 9 Higher, Q15(d) (3 marks): The number of moles in a different mass of copper oxide is 0.045. 2CuO + C 2Cu + CO2 Calculate the maximum mass of copper, Cu, that can be made from 0.045 moles
June 2024, Chemistry Paper 10 Higher, Q11(d) (2 marks): During the purification, aluminium oxide, Al 2O3, is produced from aluminium hydroxide, Al (OH)3. Complete the balanced symbol equation for the reaction. Al (OH
June 2023, Chemistry Paper 3 Foundation, Q7 (1 mark): The law of conservation of mass states that the total mass stays the same during a chemical reaction. Which is an explanation for the law of conservation of mas
June 2023, Chemistry Paper 3 Foundation, Q10 (1 mark): A metal oxide has the formula X2O, where X is a Group 1 metal. The relative formula mass of the metal oxide is 94.2. Relative atomic mass (Ar): O = 16.0 What is
June 2023, Chemistry Paper 3 Foundation, Q14(a) (1 mark): Write the balanced symbol equation for the reaction of zinc with sulfuric acid. [1]
June 2023, Chemistry Paper 3 Foundation, Q14(d)(i) (1 mark): Calculate the relative formula mass of ZnSO4. Relative atomic mass (Ar): O = 16.0 S = 32.1 Zn = 65.4 Relative formula mass of ZnSO4 = [1]
June 2023, Chemistry Paper 3 Foundation, Q14(d)(ii) (3 marks): The percentage mass of an element in a compound can be calculated using the formula total relative atomic mass of the element percentage mass of an element = re
June 2023, Chemistry Paper 4 Foundation, Q16(b) (2 marks): Complete the balanced symbol equation for the reaction. Mg(s) + 2HCl( ) → (aq) + H2(g) [2]
June 2023, Chemistry Paper 9 Higher, Q2 (1 mark): A metal oxide has the formula X2O, where X is a Group 1 metal. The relative formula mass of the metal oxide is 94.2. Relative atomic mass (Ar): O = 16.0 What is
June 2023, Chemistry Paper 9 Higher, Q8 (1 mark): Lead, Pb, and dilute nitric acid, HNO3 react. Pb + xHNO3 Pb(NO3)2 + yNO2 + zH2O Which row correctly balances the equation? x y z A 2 4 2 B 4 2 4 C 4 2 2 D 4 4 2
June 2023, Chemistry Paper 9 Higher, Q9 (1 mark): This is the symbol for helium. 2 He 4.0 What is the mass of one atom of helium? The Avogadro constant = 6.02 × 1023 A 3.32 × 10–24 g B 6.64 × 10–24 g C 1.51 × 1
June 2023, Chemistry Paper 9 Higher, Q15(e) (4 marks): Calculate the mass of hydrochloric acid, HCl , in 100 cm3 of solution that gives a pH 1.5. Use data from the graph. Give your answer to 2 significant figures. R
June 2023, Chemistry Paper 10 Higher, Q11(b) (2 marks): Complete the balanced symbol equation for the reaction. Mg(s) + 2HCl( ) → (aq) + H2(g) [2]
June 2023, Chemistry Paper 10 Higher, Q15(d) (2 marks): 0.13 g of iodine is produced from 5.0 g of seaweed. Calculate the percentage mass of iodine in the seaweed. Percentage mass of iodine = % [2]
June 2022, Chemistry Paper 3 Foundation, Q9 (1 mark): A molecule of glucose has the molecular formula C6H12O6. What is the empirical formula of glucose? A CHO B CH2O C C6H12O6 D (CO6)H12 Your answer [1]
June 2022, Chemistry Paper 3 Foundation, Q11(a) (3 marks): Complete each sentence to describe the formation of nitrogen dioxide. Use the words or phrases in the list. break apart change of state chemical change dissolve
June 2022, Chemistry Paper 3 Foundation, Q11(b) (1 mark): The equation shows the formation of nitrogen dioxide. N2 + ….. O2 ….. NO2 Complete the balanced symbol equation for the reaction. Use Fig. 11.1. [1]
June 2022, Chemistry Paper 3 Foundation, Q11(d) (2 marks): A molecule of nitrogen dioxide has the formula NO2. Calculate the relative formula mass for nitrogen dioxide. Relative atomic mass (Ar): N = 14.0 O = 16.0 Relat
June 2022, Chemistry Paper 3 Foundation, Q13(a) (1 mark): Complete the table with an estimate of the missing mass at 3 minutes. Write your answer in the box in Table 13.1. [1]
June 2022, Chemistry Paper 3 Foundation, Q13(b) (3 marks): The equation shows the reaction between magnesium, Mg, and dilute sulfuric acid, H2SO4. Mg(s) + H2SO4(aq) MgSO4(aq) + H2(g) Describe and explain how the mass ch
June 2022, Chemistry Paper 3 Foundation, Q13(c) (1 mark): The student thinks that the results show that all the magnesium had reacted. Explain why the student is correct. Use data from Table 13.1. [1]
June 2022, Chemistry Paper 3 Foundation, Q13(d) (3 marks): The student repeats the experiment three times. Table 13.2 shows the results of the three experiments at 1 minute. Table 13.2 Mass in experiment 1 Mass in exper
June 2022, Chemistry Paper 9 Higher, Q1 (1 mark): A molecule of glucose has the molecular formula C6H12O6. What is the empirical formula of glucose? A CHO B CH2O C C6H12O6 D (CO)6H12 Your answer [1]
June 2022, Chemistry Paper 9 Higher, Q10 (1 mark): What is the definition of the mole? A One mole contains 1 g of atoms. One mole contains 6.022 × 1023 particles. B C One mole is equal to the relative atomic mas
June 2022, Chemistry Paper 9 Higher, Q14(c)(i) (3 marks): Write the balanced symbol equation for the reaction of calcium with water. Include state symbols in your equation. [3]
June 2022, Chemistry Paper 9 Higher, Q14(d)(i) (3 marks): Calculate the number of moles in 1.88 g of calcium hydroxide. Give your answer to 2 significant figures. Relative atomic mass (Ar): H = 1.0 O = 16.0 Ca = 40.1 N
June 2022, Chemistry Paper 9 Higher, Q14(d)(ii) (2 marks): Use your answer to part (d)(i) to calculate the concentration of calcium hydroxide in the solution formed. Give your answer in mol / dm3. Concentration of solut
November 2021, Chemistry Paper 3 Foundation, Q5 (1 mark): Which equation shows that the mass of the solid decreases as the solid reacts? A Ca(s) + Cl 2(g) CaCl 2(s) B CaCO3(s) CaO(s) + CO2(g) C 2Cu(s) + O2(g) 2CuO(s) D
November 2021, Chemistry Paper 3 Foundation, Q7 (1 mark): Which molecule has the empirical formula CH2O? A H O H C C H H B H H H C C OH H H C H O H C C OH H D H O H H H C C O C C H H H H Your answer [1]
November 2021, Chemistry Paper 3 Foundation, Q12(a) (1 mark): Which compound, A, B, C, D or E, is made from copper, carbon and oxygen? [1]
November 2021, Chemistry Paper 3 Foundation, Q12(d) (2 marks): Calculate the relative formula mass of compound D. The relative atomic mass, Ar , of Cu is 63.5 and of S is 32.1 Relative formula mass = [2]
November 2021, Chemistry Paper 3 Foundation, Q15(a) (1 mark): Complete the balanced symbol equation for the reaction of sodium and chlorine to make sodium chloride. Na(s) + Cl 2(g) NaCl (s) [1]
November 2021, Chemistry Paper 3 Foundation, Q15(d)(i) (1 mark): Write in the table the state symbol for the solution of sodium chloride. [1]
November 2021, Chemistry Paper 4 Foundation, Q14(a) (1 mark): Calculate the mass of water produced in the experiment. Mass of water = g [1]
November 2021, Chemistry Paper 4 Foundation, Q14(b) (1 mark): The student expected a greater mass of water to be produced. How could they improve the experiment so a greater mass of water vapour is produced? [1]
November 2021, Chemistry Paper 4 Foundation, Q14(c)(i) (2 marks): Complete and balance the symbol equation. [2]
November 2021, Chemistry Paper 9 Higher, Q7 (1 mark): A student completely reacts 0.403 g of magnesium oxide with an excess of carbon. 2MgO(s) + C(s) 2Mg(s) + CO2(g) What is the mass of magnesium made? The relative
November 2021, Chemistry Paper 9 Higher, Q10 (1 mark): Which term is defined as ‘The sum of the relative atomic masses of all the atoms in a chemical formula’? A Mass number B Molecular formula C Relative formula ma
November 2021, Chemistry Paper 9 Higher, Q16(a) (2 marks): Define the term mole. [2]
November 2021, Chemistry Paper 9 Higher, Q16(b)(i) (3 marks): Calculate the number of moles of iron, steam and hydrogen. Give your answers to 2 decimal places. The relative atomic mass, Ar , of H is 1.0, of O is 16.0 and o
November 2021, Chemistry Paper 9 Higher, Q16(b)(ii) (2 marks): Look at the reaction equation. It shows the formation of 1 mole of the oxide of iron, FexOy. Fe(s) + H2O(g) FexOy(s) + H2(g) Use your answers to (b)(i) to balan
November 2020, Chemistry Paper 3 Foundation, Q7 (1 mark): Look at the molecule below. 7 ,0 ,H B B B-O H What is the empirical formula of the molecule? А ВНО В ВНО2 С Вз(ОН)з • ВзНзОз Your answer [1]
November 2020, Chemistry Paper 3 Foundation, Q11(c)(i) (2 marks): Complete the balanced symbol equation for the reaction of magnesium with oxygen. ...Mg + → • MgO 12]
November 2020, Chemistry Paper 3 Foundation, Q17(b) (2 marks): Magnesium carbonate, MgCOz, reacts with dilute hydrochloric acid, HCI. Magnesium chloride, MgClz, water and carbon dioxide are made. Write the balanced symbol e
November 2020, Chemistry Paper 3 Foundation, Q17(c)(i) (2 marks): Calculate the relative atomic mass of X. A, Mg = 24.3 Relative atomic mass of X = .[2]
November 2020, Chemistry Paper 3 Foundation, Q17(c)(ii) (1 mark): Identify element X. Use the Periodic Table on the Data Sheet to help you. • [1]
November 2020, Chemistry Paper 4 Foundation, Q7 (1 mark): Copper can be made by heating copper(I) sulfide in air. 7 Look at the equation. Cu,S + 02 → 2Cu + X What is the formula of X? A CuS BS C 502 D S03 [1] Your answ
November 2020, Chemistry Paper 9 Higher, Q7 (1 mark): What is the number of atoms in 0.0485 moles of carbon? The Avogadro constant = 6.02 × 1023. 8.05 × 10–26 A 2.92 × 1022 B 6.02 × 1023 C 1.24 × 1025 D Your answer
November 2020, Chemistry Paper 9 Higher, Q10 (1 mark): A student dissolves 5 × 10–3 moles of sodium hydroxide, NaOH, in 250 cm3 of water. What is the mass of sodium hydroxide in 25 cm3 of the solution? Relative form
November 2020, Chemistry Paper 9 Higher, Q12(b) (2 marks): Magnesium carbonate, MgCO3, reacts with dilute hydrochloric acid, HCl. Magnesium chloride, MgCl 2, water and carbon dioxide are made. Write the balanced symbol
November 2020, Chemistry Paper 9 Higher, Q12(c)(i) (2 marks): Calculate the relative atomic mass of X. Ar Mg = 24.3 Relative atomic mass of X = [2]
November 2020, Chemistry Paper 9 Higher, Q12(c)(ii) (1 mark): Identify element X. Use the Periodic Table on the Data Sheet to help you. [1]
November 2020, Chemistry Paper 9 Higher, Q14(d)(i) (3 marks): Calculate the number of moles of copper oxide, CuO, in 0.500 g. Give your answer to 3 significant figures. Number of moles of copper oxide = mol [3]
November 2020, Chemistry Paper 9 Higher, Q14(d)(ii) (2 marks): Use your answer to (d)(i) and the balanced symbol equation to explain why the copper oxide is in excess. [2]
November 2020, Chemistry Paper 9 Higher, Q16(c) (2 marks): Complete the balanced symbol equation for the reaction between phosphoric acid and calcium hydroxide. ………..H3PO4 + ……….Ca(OH)2 Ca3(PO4)2 + ……….. H2O [2]
June 2019, Chemistry Paper 3 Foundation, Q2 (1 mark): The equation shows the reaction of sodium with water. Sodium hydroxide and hydrogen are made. Two of the state symbols are missing. 2Na(s) + 2H2O 2NaOH(aq) + H2
June 2019, Chemistry Paper 3 Foundation, Q4 (1 mark): What is the relative formula mass of sulfuric acid, H2SO4? The relative atomic mass, Ar, of H is 1.0, of S is 32.1 and of O is 16.0. A 49.1 B 81.2 C 98.1 D 129.
June 2019, Chemistry Paper 3 Foundation, Q7 (1 mark): Calcium carbonate, CaCO3, decomposes when heated. Calcium oxide, CaO, and carbon dioxide, CO2, are made. Look at the equation for the reaction. CaCO3 CaO + CO2
June 2019, Chemistry Paper 3 Foundation, Q8 (1 mark): The molecular formula of a compound is C12H26. What is its empirical formula? A C2H4 B C2H6 C C4H6 D C6H13 Your answer [1]
June 2019, Chemistry Paper 3 Foundation, Q9 (1 mark): Phosphorus sulfide, P4S3, has a relative formula mass of 220.3. What is the percentage, by mass, of phosphorus in P4S3? Use the Periodic Table to help you. A 6.
June 2019, Chemistry Paper 3 Foundation, Q14(a) (1 mark): What is the empirical formula of salicylic acid? [1]
June 2019, Chemistry Paper 3 Foundation, Q15(b)(i) (3 marks): Calculate the relative atomic mass of metal M. Use the equation: relative atomic mass of metal M = relative atomic mass of copper × mass of metal M mass of copp
June 2019, Chemistry Paper 3 Foundation, Q15(b)(ii) (1 mark): Use your answer from (b)(i) and the Periodic Table to identify the metal M. [1]
June 2019, Chemistry Paper 4 Foundation, Q11(c)(i) (1 mark): Balance the equation for this reaction. [1] KBr + Cl 2 KCl + Br2
June 2019, Chemistry Paper 4 Foundation, Q12(d) (3 marks): The table shows some relative atomic masses. Element Relative atomic mass Sulfur 32.1 Oxygen 16.0 Calculate the percentage, by mass, of oxygen in SO2. Give your
June 2019, Chemistry Paper 4 Foundation, Q13(c)(ii) (2 marks): A student burns 10.0 g of hexane. Flame Evaporating dish Hexane Heatproof mat These are his results. Mass of hexane before burning = 10.0 g Mass of hexane after
June 2019, Chemistry Paper 4 Foundation, Q16(a) (2 marks): Write a balanced symbol equation for this reaction. [2]
June 2019, Chemistry Paper 9 Higher, Q10 (1 mark): What is the mass of 2 moles of calcium hydroxide? A 148.2 g B 164.1 g C 220.1 g D 328.2 g Your answer [1] SECTION B Answer all the questions.
June 2019, Chemistry Paper 9 Higher, Q13(c)(i) (1 mark): What is the empirical formula of phosphorus pentoxide? [1]
June 2019, Chemistry Paper 9 Higher, Q13(d)(i) (1 mark): Calculate the moles of magnesium used in the experiment. Moles of magnesium = [1]
June 2019, Chemistry Paper 9 Higher, Q13(d)(ii) (3 marks): Calculate the relative atomic mass of metal M. Give your answer to 3 significant figures. Relative atomic mass of metal M = [3]
June 2019, Chemistry Paper 9 Higher, Q13(d)(iii) (1 mark): Use your answer from (d)(ii) and the Periodic Table to identify the metal M. [1]
June 2019, Chemistry Paper 9 Higher, Q15(b)(i) (4 marks): Calculate the number of molecules in 20.0 g of hex-1-ene. Avogadro’s constant = 6.02 × 1023 mol–1 Give your answer to 3 significant figures. Number of molecules
June 2019, Chemistry Paper 9 Higher, Q15(b)(ii) (1 mark): Hex-1-ene was burned using a spirit burner in the laboratory. The diagram shows the spirit burner. hex-1-ene Burning 20.0 g of hex-1-ene should produce 62.9 g o
June 2019, Chemistry Paper 10 Higher, Q10 (1 mark): Chlorine is in Group 7 of the Periodic Table. What is the mass of 2 moles of chlorine gas? A 35.5g B 71.0g C 106.5g D 142.0g Your answer [1] SECTION B Answer al
June 2019, Chemistry Paper 10 Higher, Q12(a) (2 marks): Write a balanced symbol equation for this reaction. [2]
June 2019, Chemistry Paper 10 Higher, Q15(a) (4 marks): The table shows some relative atomic masses. Element Relative atomic mass sulfur 32.1 oxygen 16.0 Calculate the maximum mass of SO3, in g, that can be made from
June 2018, Chemistry Paper 3 Foundation, Q14(a) (1 mark): Write down the empirical formula for this molecule. [1]
June 2018, Chemistry Paper 3 Foundation, Q14(b) (1 mark): Calculate the relative formula mass, Mr, for this molecule. Answer = [1]
June 2018, Chemistry Paper 3 Foundation, Q19(c)(i) (1 mark): Balance the equation for this reaction. Al2S3 + HCl → Al Cl3 + H2S [1]
June 2018, Chemistry Paper 9 Higher, Q1 (1 mark): Which statement is correct about a chemical change? A A solid changes to a liquid. B No new substances are formed. C The change is irreversible. D The change is
June 2018, Chemistry Paper 9 Higher, Q6 (1 mark): Look at the equation. H2SO4 + xNH4OH → (NH4)2SO4 + yH2O Which values of x and y balance the equation? A x = 1 and y = 1 B x = 1 and y = 2 C x = 2 and y = 1 D x
June 2018, Chemistry Paper 9 Higher, Q9 (1 mark): How many atoms of an element does one mole contain? 6.02214086 × 1023 A 6.02214086 × 10–23 B 9.02214086 × 1023 C 9.02214086 × 1026 D Your answer [1]
June 2018, Chemistry Paper 9 Higher, Q10 (1 mark): The relative formula mass of NaOH is 40. What mass of sodium hydroxide, NaOH, is found in 100 cm3 of a 0.5 mol / dm3 solution of NaOH? A 0.2 g B 0.4 g C 2.0 g D
June 2018, Chemistry Paper 9 Higher, Q12(c)(i) (1 mark): Balance the equation for this reaction. Al2S3 + HCl → AlCl3 + H2S [1]
June 2018, Chemistry Paper 9 Higher, Q18 (2 marks): Ammonium carbonate reacts with nitric acid. Ammonium nitrate, water and carbon dioxide are made. Look at the equation for the reaction. (NH4)2CO3 + 2HNO3 → 2NH4
June 2018, Chemistry Paper 10 Higher, Q18(d) (3 marks): Sulfur dioxide for this reaction is made by burning sulfur. S(s) + O2(g) SO2(g) Calculate the mass of sulfur needed to make 48 tonnes of sulfur dioxide. Give yo

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