2024 Cambridge IGCSE Chemistry (0620) Practice Paper with Answers

A student prepares a sample of hydrated copper(II) sulfate crystals by reacting excess copper(II) oxide with dilute sulfuric acid.

Why is excess copper(II) oxide added?

Molten lead(II) bromide is electrolysed using inert carbon electrodes.

Which row correctly describes the products formed at the electrodes?

Which statement about addition polymerisation is correct?

Molten lead(II) bromide is electrolysed using inert carbon electrodes. Which row correctly describes the products and observations at each electrode?

Which sequence of experimental steps is used to prepare a pure, dry sample of hydrated copper(II) sulfate crystals from insoluble copper(II) oxide and dilute sulfuric acid?

Ethene is a monomer that can be polymerised to form poly(ethene). Which statement about this polymerisation and the polymer formed is correct?

A student performs a paper chromatography experiment to analyze a black ink. The starting line is drawn in pencil and a spot of ink is placed on it. After running the chromatogram, the solvent front has moved \(8.0\text{ cm}\) from the starting line. The ink separates into two spots. The distance from the starting line to the center of the faster-moving spot is \(6.0\text{ cm}\). What is the \(R_f\) value of this spot?

Dilute hydrochloric acid is added to a solid substance in a test-tube. Rapid effervescence is observed, and the gas produced turns limewater cloudy. Which substance was added to the acid?

Which statement describes the trends in the physical state at room temperature and the reactivity of the Group VII elements (halogens) as the group is descended (from fluorine to iodine)?

A student has a mixture of sand and solid copper(II) sulfate. The student wants to obtain a pure, dry sample of copper(II) sulfate crystals. Which sequence of steps should the student use?

Molten lead(II) bromide is electrolysed using inert carbon electrodes. Which statement about this electrolysis is correct?

Ethene, \(\text{C}_2\text{H}_4\), reacts to form the polymer poly(ethene). Which row describes the type of polymerisation reaction and the change in bonding that occurs?

A mixture contains insoluble sand, soluble sodium chloride, and water. Which sequence of processes will produce a pure sample of dry sand and a pure sample of dry sodium chloride crystals?

Aqueous chlorine is added to a test-tube containing aqueous potassium bromide. What is the observation and the correct explanation for this reaction?

A student is given two separate tubes: one contains ethane gas and the other contains ethene gas. Which test and observation can be used to identify the tube containing ethene?

Why is the baseline (start line) on a chromatography paper drawn in pencil rather than in ink?

Which statement describes the trends in the physical properties of the Group VII halogens as the group is descended (from fluorine to iodine)?

A student wants to separate a mixture of solid copper(II) oxide (insoluble in water) and solid sodium chloride (soluble in water) to obtain pure, dry samples of both.

Which sequence of steps should the student use?

A student prepares a pure, dry sample of copper(II) sulfate crystals. They add excess copper(II) oxide to hot dilute sulfuric acid. Which sequence of steps should the student carry out next to obtain pure, dry crystals of copper(II) sulfate?

Molten lead(II) bromide is electrolyzed using inert carbon electrodes. What are the observations at the anode (positive electrode) and at the cathode (negative electrode)?

Which row correctly identifies the method used to obtain pure water from sea water, and ethanol from a mixture of ethanol and water?

A solid mixture contains insoluble barium sulfate and soluble sodium chloride. Which sequence of steps is used to obtain a pure, dry sample of barium sulfate from this mixture?

An atom of sodium has a nucleon (mass) number of 23 and a proton number of 11. Which option correctly shows the number of protons, neutrons and electrons in a sodium ion, \(\text{Na}^+\)?

Molten lead(II) bromide is electrolysed using inert carbon electrodes. Which row correctly describes the products formed at the positive electrode (anode) and the negative electrode (cathode)?

Molten lead(II) bromide is electrolysed using inert carbon electrodes. Which row correctly describes the product and observation at each electrode?

An atom of sodium has a proton number of 11 and a nucleon number of 23. How many protons, neutrons and electrons are in this neutral atom?

Which statement about the Group VII elements (halogens) is correct?

A student wants to prepare pure, dry crystals of copper(II) sulfate by reacting excess copper(II) oxide with dilute sulfuric acid. Which sequence of steps should be carried out after the reaction is complete?

Molten lead(II) bromide is electrolysed using inert carbon electrodes. Which observations are made at the anode and at the cathode?

Which statement about the polymerisation of ethene to form poly(ethene) is correct?

Molten lead(II) bromide is electrolysed using inert graphite electrodes. What is formed at each electrode?

Which statement about synthetic polymers is correct?

Which row correctly identifies a major source of carbon monoxide and a major source of sulfur dioxide as air pollutants?

A student tests an aqueous solution of an unknown salt X. The addition of aqueous sodium hydroxide to a sample of the solution produces a green precipitate that is insoluble in excess. The addition of dilute nitric acid followed by aqueous silver nitrate to another sample produces a cream precipitate. What is the identity of salt X?

An insoluble salt, lead(II) sulfate, needs to be prepared. Which pair of reactants is most suitable to prepare a pure sample of lead(II) sulfate?

Chlorine gas is bubbled into an aqueous solution of potassium bromide. Which statement correctly describes the observation and explains the reaction?

An experiment is set up to electrolyse molten lead(II) bromide using inert carbon electrodes. Which observations are made at the electrodes?

A student prepares a pure sample of hydrated copper(II) sulfate crystals by reacting excess copper(II) oxide with warm dilute sulfuric acid. Which sequence of steps should the student use after the reaction is complete?

Which statement describes the addition polymerisation of ethene to form poly(ethene)?

An aqueous solution of salt \(X\) is tested.

- The addition of aqueous sodium hydroxide produces a green precipitate that is insoluble in excess.
- The addition of dilute nitric acid followed by aqueous silver nitrate produces a cream precipitate.

What is the identity of salt \(X\)?

Which statement about the relative atomic mass of an element is correct?

Concentrated aqueous sodium chloride is electrolysed using inert carbon electrodes. Which row correctly identifies the product formed at each electrode and the change in pH of the electrolyte surrounding the cathode?

The structure of a monomer is shown.

\(\text{CH}_2=\text{CH}-\text{COOCH}_3\)

Which formula represents the repeating unit of the addition polymer formed from this monomer?

A sample of 1.20 g of magnesium ribbon is reacted completely with an excess of dilute hydrochloric acid.

\(\text{Mg(s)} + 2\text{HCl(aq)} \rightarrow \text{MgCl}_2\text{(aq)} + \text{H}_2\text{(g)}\)

What is the volume of hydrogen gas produced, measured at room temperature and pressure (r.t.p.)?

[Relative atomic mass: \(\text{Mg} = 24.0\); molar volume of any gas at r.t.p. is \(24.0\text{ dm}^3/\text{mol}\)]

During the electrolysis of concentrated aqueous sodium chloride using inert graphite electrodes, reactions occur at both the anode and the cathode. Which row correctly identifies the substance produced at each electrode and the change in pH of the electrolyte immediately surrounding the cathode?

A student titrates \(25.0\text{ cm}^3\) of \(0.0500\text{ mol/dm}^3\) aqueous sodium hydroxide, \(\text{NaOH}\), with dilute sulfuric acid, \(\text{H}_2\text{SO}_4\).

\[ 2\text{NaOH(aq)} + \text{H}_2\text{SO}_4\text{(aq)} \rightarrow \text{Na}_2\text{SO}_4\text{(aq)} + 2\text{H}_2\text{O(l)} \]

The volume of sulfuric acid required to neutralize the sodium hydroxide is \(20.0\text{ cm}^3\).

What is the concentration of the sulfuric acid?

Which statement correctly describes addition polymerization or condensation polymerization?

Two different electrolysis experiments are set up:

- Experiment 1: Electrolysis of concentrated aqueous sodium chloride using inert carbon electrodes.
- Experiment 2: Electrolysis of dilute sulfuric acid using inert carbon electrodes.

Which products are formed at the positive electrodes (anodes) in each experiment?

Which method is most suitable for preparing a pure, dry sample of the insoluble salt, barium sulfate, \(\text{BaSO}_4\)?

A condensation polymer is made from a dicarboxylic acid monomer, \(\text{HOOC-CH}_2\text{-COOH}\), and a diol monomer, \(\text{HO-CH}_2\text{-CH}_2\text{-OH}\).

Which structure represents the repeating unit of the polyester formed?

Concentrated aqueous sodium chloride is electrolysed using inert carbon electrodes. Which row correctly identifies the products formed at each electrode and the change in pH of the electrolyte in the region surrounding the cathode?

How many total ions are present in \(0.10\text{ mol}\) of iron(III) sulfate, \(\text{Fe}_2(\text{SO}_4)_3\)? (The Avogadro constant, \(L\), is \(6.02 \times 10^{23}\text{ mol}^{-1}\).)

A section of a synthetic polymer is shown:

\[ -\text{O}-\text{CH}_2-\text{CH}_2-\text{O}-\text{CO}-\text{C}_6\text{H}_4-\text{CO}-\text{O}-\text{CH}_2-\text{CH}_2-\text{O}-\text{CO}-\text{C}_6\text{H}_4-\text{CO}- \]

Which row correctly identifies the types of monomer used to make this polymer and the classification of the polymer?

Concentrated aqueous sodium chloride is electrolysed using inert carbon electrodes. Which row correctly describes the substance produced at the anode and the change in pH of the electrolyte?

A student carries out tests on a green solid, \(X\). When dilute hydrochloric acid is added to solid \(X\), a gas is evolved that turns acidified aqueous potassium manganate(VII) from purple to colourless. When aqueous sodium hydroxide is added to a solution of \(X\), a green precipitate is formed which remains insoluble in excess sodium hydroxide. What is the identity of solid \(X\)?

An aqueous solution contains \(0.10\text{ mol}\) of aluminium sulfate, \(\text{Al}_2(\text{SO}_4)_3\). What is the total number of ions present in this solution? (The Avogadro constant, \(L = 6.02 \times 10^{23}\text{ /mol}\))

Concentrated aqueous sodium chloride is electrolysed using inert carbon electrodes. Which row correctly describes the products formed at each electrode and the change in pH of the electrolyte?

An aqueous solution of copper(II) sulfate is electrolysed using two different setups. Setup 1: Copper electrodes are used. Setup 2: Platinum (inert) electrodes are used. Which row correctly describes the observations at the anode (positive electrode) in each setup?

How many total ions are present in \(200\text{ cm}^3\) of \(0.40\text{ mol/dm}^3\) aqueous iron(III) sulfate, \(\text{Fe}_2(\text{SO}_4)_3\)? (Avogadro constant, \(L = 6.0 \times 10^{23}\text{ /mol}\))

A synthetic polymer has the structure shown: \(\text{[-O-CH}_2\text{-CH}_2\text{-O-CO-C}_6\text{H}_4\text{-CO-]_n}\). Which statement about this polymer is correct?

An aqueous solution of copper(II) sulfate is electrolysed using different electrodes. In Experiment 1, inert carbon (graphite) electrodes are used. In Experiment 2, copper electrodes are used. Which row correctly describes the observations at the anode (+ electrode) in each experiment?

A student titrates \( 25.0\text{ cm}^3 \) of \( 0.0500\text{ mol/dm}^3 \) aqueous sodium hydroxide, \( \text{NaOH} \), with dilute sulfuric acid, \( \text{H}_2\text{SO}_4 \). The equation for the reaction is: \( 2\text{NaOH}(aq) + \text{H}_2\text{SO}_4(aq) \rightarrow \text{Na}_2\text{SO}_4(aq) + 2\text{H}_2\text{O}(l) \) The average titre volume of sulfuric acid required for complete neutralisation is \( 20.0\text{ cm}^3 \). What is the concentration of the sulfuric acid?

A student wishes to prepare a pure, dry sample of the insoluble salt lead(II) sulfate, \( \text{PbSO}_4 \). Which pair of reactants and experimental method should be used?

Concentrated aqueous sodium chloride is electrolysed using inert carbon electrodes. Which row correctly identifies the products formed at each electrode and the change in the pH of the remaining solution?

| | Cathode (-) | Anode (+) | pH of remaining solution |
|--- | --- | --- | --- |
| A | hydrogen | chlorine | increases |
| B | sodium | chlorine | decreases |
| C | hydrogen | oxygen | remains constant |
| D | sodium | oxygen | increases |

Hydrogen sulfide reacts with oxygen according to the equation shown:

\( 2\text{H}_2\text{S(g)} + 3\text{O}_2\text{(g)} \rightarrow 2\text{SO}_2\text{(g)} + 2\text{H}_2\text{O(l)} \)

\( 40\text{ cm}^3 \) of hydrogen sulfide is mixed with \( 80\text{ cm}^3 \) of oxygen. The mixture is ignited and allowed to react. All gas volumes are measured at room temperature and pressure.

What is the total volume of gas remaining after the reaction is complete?

A synthetic polymer has the structural segment shown:

\( -\text{O}-\text{CH}_2-\text{CH}_2-\text{O}-\text{CO}-\text{C}_6\text{H}_4-\text{CO}-\text{O}-\text{CH}_2-\text{CH}_2-\text{O}- \)

Which statement about this polymer is correct?

A student wants to prepare a pure, dry sample of copper(II) sulfate crystals starting from the insoluble base copper(II) carbonate. Which sequence of steps should the student follow?

A condensation polymer is formed by reacting a dicarboxylic acid monomer with a diol monomer. Which linkage is formed in this polymer, and which small molecule is eliminated during the reaction?

Concentrated aqueous sodium chloride is electrolysed using inert carbon electrodes. Which products are formed at the electrodes, and how does the pH of the remaining solution change?

Concentrated aqueous sodium chloride is electrolysed using inert carbon electrodes.

Which row correctly identifies the product at each electrode and the change in pH of the electrolyte immediately surrounding the cathode?

| | Product at cathode | Product at anode | pH near cathode |
| :--- | :--- | :--- | :--- |
| **A** | hydrogen | chlorine | increases |
| **B** | sodium | chlorine | decreases |
| **C** | hydrogen | oxygen | remains unchanged |
| **D** | oxygen | chlorine | increases |

A student carries out a titration to find the concentration of a sample of sulfuric acid, \(\text{H}_2\text{SO}_4\).

\(25.0\text{ cm}^3\) of the sulfuric acid is neutralised exactly by \(20.0\text{ cm}^3\) of \(0.150\text{ mol/dm}^3\) sodium hydroxide, \(\text{NaOH}\).

The equation for the reaction is:

\[ \text{H}_2\text{SO}_4(\text{aq}) + 2\text{NaOH}(\text{aq}) \rightarrow \text{Na}_2\text{SO}_4(\text{aq}) + 2\text{H}_2\text{O}(\text{l}) \]

What is the concentration of the sulfuric acid?

The diagram shows the structure of a section of a polymer chain.

\[ \text{---O---CH}_2\text{---CH}_2\text{---O---C}(=\text{O})\text{---CH}_2\text{---CH}_2\text{---C}(=\text{O})--- \]

Which monomers are used to form this polymer?

A student prepares a pure sample of hydrated copper(II) sulfate crystals, \(\text{CuSO}_4 \cdot 5\text{H}_2\text{O}\), from copper(II) oxide and dilute sulfuric acid. Which sequence of steps produces a pure, dry sample of the crystals?

Concentrated aqueous sodium chloride is electrolysed using inert carbon electrodes. Which row correctly identifies the product at each electrode and the change in pH of the electrolyte during the electrolysis?

A sample of \(4.0\text{ g}\) of a gaseous hydrocarbon occupies a volume of \(2.4\text{ dm}^3\) at room temperature and pressure (r.t.p.). [Molar volume of gas at r.t.p. is \(24\text{ dm}^3/\text{mol}\)] What is the molecular formula of the hydrocarbon?

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A \(0.10\text{ mol}\) sample of a gaseous hydrocarbon, \(X\), is completely burned in an excess of oxygen. This combustion produces \(8.8\text{ g}\) of carbon dioxide, \(\text{CO}_2\), and \(5.4\text{ g}\) of water, \(\text{H}_2\text{O}\). What is the molecular formula of hydrocarbon \(X\)? [Relative atomic masses, \(A_r\): \(\text{H} = 1\); \(\text{C} = 12\); \(\text{O} = 16\)]

A student investigates a mixture of colored food dyes using paper chromatography.

(a) (i) Explain why the start line on the chromatography paper is drawn in pencil rather than ink. [1]
(ii) Explain why the level of the solvent in the beaker must be below the start line. [1]
(iii) Amino acids can be separated by chromatography but are colorless. State the term for the substance that must be sprayed on the chromatogram to make the amino acids visible. [1]
(iv) One of the dyes travels a distance of \(5.2\text{ cm}\) from the start line. The solvent front travels a distance of \(8.0\text{ cm}\) from the start line. Calculate the \(R_f\) value of this dye. Show your working. [2]

(b) Match the correct method of separation from the list below to each of the following mixtures: [3]
- Method A: Filtration
- Method B: Simple distillation
- Method C: Fractional distillation
- Method D: Crystallisation

(i) Obtaining pure water from seawater.
(ii) Separating sand from a mixture of sand and water.
(iii) Separating ethanol from a mixture of ethanol and water.

(c) State how a student could test if a sample of liquid is pure water using its physical properties. [2]

This question is about atoms, isotopes, and the Periodic Table.

(a) Complete the table below to show the structure of the given particles. [3]

| Particle | Number of protons | Number of neutrons | Number of electrons |
| :--- | :---: | :---: | :---: |
| Carbon-14 atom (\(^{14}_{6}\text{C}\)) | 6 | **(i)** | 6 |
| Sodium ion (\(^{23}_{11}\text{Na}^+\)) | 11 | 12 | **(ii)** |
| Oxygen atom (\(^{16}_{8}\text{O}\)) | **(iii)** | 8 | 8 |

(b) Define the term 'isotopes'. [2]

(c) A phosphorus-31 atom is represented by the symbol \(^{31}_{15}\text{P}\).
(i) Deduce the number of protons and neutrons in one atom of \(^{31}_{15}\text{P}\). [2]
Protons: ______
Neutrons: ______
(ii) State the electronic configuration of a phosphorus atom. [1]

(d) Explain, in terms of electronic configuration, why the elements in Group VIII (Group 0) of the Periodic Table are very unreactive. [2]

Electrolysis is a useful process for breaking down ionic substances using electricity.

(a) (i) State what is meant by the term 'electrolysis'. [2]
(ii) Name a suitable material that can be used for inert electrodes in a school laboratory. [1]

(b) Lead(II) bromide, \(\text{PbBr}_2\), is electrolysed using inert electrodes.
(i) Explain why solid lead(II) bromide does not conduct electricity, whereas molten lead(II) bromide does. [2]
(ii) Describe the observation and name the product formed at the negative electrode (cathode) during the electrolysis of molten lead(II) bromide. [2]
Observation: ______
Product name: ______
(iii) Describe the observation and name the product formed at the positive electrode (anode) during the electrolysis of molten lead(II) bromide. [2]
Observation: ______
Product name: ______

(c) During the industrial extraction of aluminium by electrolysis, state the name of the main ore from which aluminium oxide is obtained. [1]

This question is about the Group VII elements and their structures.

(a) State the group number of the halogens. [1]

(b) Describe the trend in reactivity of the Group VII elements down the group. [1]

(c) Fluorine and chlorine are in Group VII.
(i) State the number of protons, neutrons, and electrons in an atom of fluorine, \(^{19}_{9}\text{F}\). [3]
(ii) A chloride ion has the formula \(\text{Cl}^-\). State the number of electrons in a \(\text{Cl}^-\) ion. (The proton number of chlorine is 17). [1]

(d) Chlorine reacts with aqueous potassium bromide.
(i) State the observations for this reaction. [2]
(ii) Complete the word equation for this reaction:
chlorine + potassium bromide \(\rightarrow\) .................... + .................... [2]

This question is about electrolysis.

(a) Complete the sentences about the electrolysis of molten lead(II) bromide using words from the list. Each word may be used once, more than once, or not at all.

[ anode, cathode, bromine, lead, molten, oxidation, reduction ]

During electrolysis, positive ions move to the negative electrode, which is called the .................... .
At this electrode, the metal .................... is formed.
Negative ions move to the positive electrode, which is called the .................... .
At this electrode, the non-metal .................... is formed. [4]

(b) State the observations at each electrode during the electrolysis of molten lead(II) bromide:
(i) positive electrode (anode) [1]
(ii) negative electrode (cathode) [1]

(c) Inert electrodes are used in this process. State the name of a material suitable for making inert electrodes. [1]

(d) When aqueous copper(II) sulfate is electrolysed using carbon electrodes:
(i) State the product formed at the cathode. [1]
(ii) State the product formed at the anode. [1]
(iii) Describe how the appearance of the solution changes during this electrolysis. [1]

The formulas of four organic compounds, A, B, C, and D, are shown.

- Compound A: \(\text{CH}_4\)
- Compound B: \(\text{CH}_2\text{CH}_2\)
- Compound C: \(\text{CH}_3\text{CH}_2\text{OH}\)
- Compound D: \(\text{CH}_3\text{COOH}\)

(a) State which compound, A, B, C or D:
(i) is an alkene. [1]
(ii) is an alcohol. [1]
(iii) contains a carboxylic acid functional group. [1]
(iv) is a saturated hydrocarbon. [1]

(b) Describe a chemical test to distinguish between Compound A and Compound B.
test: ....................
result with Compound A: ....................
result with Compound B: .................... [3]

(c) Compound B (ethene) can be polymerised to form poly(ethene).
(i) State the type of polymerisation reaction that occurs. [1]
(ii) Complete the sentence:
Ethene is the .................... in this reaction, and poly(ethene) is the polymer. [1]
(iii) State one common use of poly(ethene). [1]

This question is about the preparation of salts.

(a) A student prepares a sample of soluble copper(II) sulfate crystals by reacting insoluble copper(II) oxide with dilute sulfuric acid.
Write the word equation for this reaction. [1]

(b) The student adds excess copper(II) oxide to the warm dilute sulfuric acid.
Explain why excess copper(II) oxide is added. [1]

(c) Describe how the excess copper(II) oxide is removed from the reaction mixture. [1]

(d) Describe the steps needed to obtain pure, dry crystals of hydrated copper(II) sulfate from the filtrate. [3]

(e) In a different experiment, the student prepares a sample of the insoluble salt, barium sulfate.
(i) Suggest the names of two soluble salts that can be reacted together to form barium sulfate. [2]
(ii) State the name of this type of reaction. [1]
(iii) State how the solid barium sulfate is separated from the reaction mixture. [1]

This question is about polymers.

(a) Poly(ethene) is a widely used synthetic addition polymer.
(i) What is meant by the term polymer? [1]
(ii) Ethene is the monomer used to make poly(ethene). State the type of covalent bond present in ethene that is broken during the polymerisation process. [1]
(iii) State one common use of poly(ethene). [1]

(b) Propene is another alkene monomer. It polymerises to form poly(propene).
Complete the table below to compare the properties of the monomer propene with the polymer poly(propene).

| Property | Monomer: Propene | Polymer: Poly(propene) |
| :--- | :--- | :--- |
| State of matter at room temperature | (i) .................... [1] | (ii) .................... [1] |
| Classification (Saturated or Unsaturated) | (iii) .................... [1] | (iv) .................... [1] |

(c) Starch is a natural polymer.
(i) Name the type of monomer unit that links together to form starch. [1]
(ii) Name one other natural polymer found in living organisms. [1]
(iii) State the process by which complex carbohydrates like starch are broken down into simple sugars in the presence of an acid catalyst. [1]

A student carries out a titration to determine the concentration of a solution of sulfuric acid, \(\text{H}_2\text{SO}_4\).

They titrate \(25.0\text{ cm}^3\) of \(0.150\text{ mol/dm}^3\) sodium hydroxide, \(\text{NaOH}\), with the sulfuric acid. The equation for the reaction is:

\[\text{H}_2\text{SO}_4\text{(aq)} + 2\text{NaOH(aq)} \rightarrow \text{Na}_2\text{SO}_4\text{(aq)} + 2\text{H}_2\text{O(l)}\]

(a) Describe how the student would carry out this titration. In your answer, include:
- the names of the apparatus used to measure the volume of \(\text{NaOH}\) and to add the acid
- how the student knows the end-point is reached using a named indicator and its color change. [5 marks]

(b) The average volume of sulfuric acid used in the titration is \(18.75\text{ cm}^3\).

(i) Calculate the number of moles of \(\text{NaOH}\) in \(25.0\text{ cm}^3\) of \(0.150\text{ mol/dm}^3\) solution. [1 mark]

(ii) Determine the number of moles of \(\text{H}_2\text{SO}_4\) that reacted with this amount of \(\text{NaOH}\). [1 mark]

(iii) Calculate the concentration of the sulfuric acid in \(\text{mol/dm}^3\). [2 marks]

(iv) Calculate the concentration of the sulfuric acid in \(\text{g/dm}^3\).

\[[A_r: \text{H} = 1; \text{S} = 32; \text{O} = 16]\] [2 marks]

(c) After the titration, the student wants to obtain pure, dry crystals of hydrated sodium sulfate, \(\text{Na}_2\text{SO}_4 \cdot 10\text{H}_2\text{O}\).

Describe the steps they should take, starting with the reaction mixture from a fresh titration performed without the indicator. [2 marks]

Electrolysis is a key chemical process used to extract metals, produce important chemicals, and electroplate objects.

(a) Molten lead(II) bromide is electrolysed using inert carbon electrodes.

(i) State the observation made at each electrode. [2 marks]
- Cathode (negative electrode):
- Anode (positive electrode):

(ii) Write the ionic half-equation, including state symbols, for the reaction occurring at the anode. [2 marks]

(b) Concentrated aqueous sodium chloride (brine) is electrolysed using inert electrodes.

(i) Identify the gaseous product formed at each electrode. [2 marks]
- Cathode:
- Anode:

(ii) Explain why sodium metal is not produced at the cathode. [1 mark]

(iii) After electrolysis has occurred for some time, the electrolyte is tested with universal indicator and found to be alkaline. Identify the ion responsible for this alkalinity and explain how it is formed during this electrolysis. [2 marks]

(c) Electroplating is used to coat a steel spoon with nickel.

(i) State what should be used as:
- the anode (positive electrode) [1 mark]
- the cathode (negative electrode) [1 mark]
- the electrolyte [1 mark]

(ii) Write the ionic half-equation for the reaction occurring at the cathode during this electroplating. [1 mark]

Polymers are macromolecules built up from small monomer units. They can be classified as addition or condensation polymers.

(a) Propene, \(\text{CH}_3\text{CH}=\text{CH}_2\), is an unsaturated hydrocarbon that can undergo addition polymerisation to form poly(propene).

(i) Draw a diagram to show the structure of a propene monomer. Show all atoms and all bonds. [1 mark]

(ii) Draw the structure of poly(propene) showing two repeat units. Show all atoms and all single bonds. [2 marks]

(iii) State the main difference between addition polymerisation and condensation polymerisation in terms of the products formed. [1 mark]

(b) Nylon is a synthetic polyamide formed by condensation polymerisation.

(i) Nylon can be made from a dicarboxylic acid and a diamine. Draw the structures of a dicarboxylic acid monomer and a diamine monomer. Use block diagrams (rectangles) to represent the carbon chains. Show the functional groups at each end. [2 marks]
- Dicarboxylic acid monomer:
- Diamine monomer:

(ii) Draw the structure of the amide linkage (peptide link) showing all atoms and bonds. [1 mark]

(iii) Identify the small molecule that is eliminated during this polymerisation. [1 mark]

(c) Terylene is a polyester.

(i) State the name of the two functional groups that react to form a polyester. [2 marks]

(ii) Draw the structure of a polyester linkage (ester link) showing all atoms and bonds. [1 mark]

(d) Many synthetic addition polymers are non-biodegradable.

(i) Explain what is meant by the term non-biodegradable and state one environmental problem associated with the disposal of these polymers in landfills. [2 marks]

A student titrates a \( 25.0\text{ cm}^3 \) sample of a diprotic acid, \( \text{H}_2\text{A} \), of unknown concentration against a standard \( 0.150\text{ mol/dm}^3 \) solution of sodium hydroxide, \( \text{NaOH} \). (a) Describe how the student should rinse and prepare the burette before filling it with the standard \( \text{NaOH} \) solution. (b) State the colour change of methyl orange indicator at the end point when the alkali is added to the acid in the conical flask. (c) The student performs three titrations and obtains the following titres: Titration 1: \( 23.40\text{ cm}^3 \), Titration 2: \( 22.80\text{ cm}^3 \), Titration 3: \( 22.90\text{ cm}^3 \). Calculate the average concordant titre to be used in subsequent calculations. (d) Write the balanced chemical equation for the reaction between \( \text{H}_2\text{A} \) and \( \text{NaOH} \). (e) Calculate the concentration of the diprotic acid, \( \text{H}_2\text{A} \), in \( \text{mol/dm}^3 \). (f) Given that the concentration of \( \text{H}_2\text{A} \) is \( 3.42\text{ g/dm}^3 \), calculate the relative molecular mass, \( M_r \), of the acid. Show your working.

Aqueous copper(II) sulfate, \( \text{CuSO}_4\text{(aq)} \), is electrolysed. (a) (i) Describe the observation at the cathode and write an ionic half-equation for the reaction occurring at this electrode when inert carbon electrodes are used. (ii) Describe the observation at the anode and write an ionic half-equation for the reaction occurring at this electrode when inert carbon electrodes are used. (b) Explain why the blue colour of the electrolyte fades and the solution eventually becomes acidic during this electrolysis with carbon electrodes. (c) The experiment is repeated using copper electrodes instead of carbon electrodes. (i) Describe the change in mass of the anode and cathode. (ii) Explain how this electrolysis setup with copper electrodes is adapted and used in the industrial purification of copper.

Polymers can be synthesized through addition or condensation polymerization. (a) State two differences between addition polymerization and condensation polymerization. (b) A polyester can be formed from a dicarboxylic acid and a diol monomer. (i) Represent the dicarboxylic acid monomer as \( \text{HOOC}-\Box-\text{COOH} \) and the diol monomer as \( \text{HO}-\bigcirc-\text{OH} \). Draw the structure of the repeating unit of the polyester formed when these two monomers react, showing the ester linkage clearly with all bonds. (ii) State the name of the small molecule eliminated during this condensation reaction. (c) Terylene is a synthetic polyester. State one common household or industrial use of Terylene. (d) Poly(lactic acid), PLA, is a biodegradable polyester. (i) Explain the environmental advantages of biodegradable plastics over non-biodegradable ones. (ii) Lactic acid has the structure \( \text{CH}_3-\text{CH(OH)}-\text{COOH} \). Explain why lactic acid can polymerize with itself to form a polyester, without needing a second monomer.

A student investigated the rate of reaction between excess calcium carbonate (marble chips) and \(50\text{ cm}^3\) of dilute hydrochloric acid, \(\text{HCl}\), at room temperature.

The apparatus used is shown below (schematic description):
A conical flask containing the reactant mixture is sealed with a stopper. A delivery tube connects the stopper of this flask to a gas syringe.

(a) Name the piece of apparatus that should be used to:
(i) measure the \(50\text{ cm}^3\) of dilute hydrochloric acid. [1]
(ii) collect and measure the volume of carbon dioxide gas produced. [1]

(b) The gas syringe readings at different times during the experiment are shown below.
- At \(0\text{ s}\): \(0\text{ cm}^3\)
- At \(30\text{ s}\): \(24\text{ cm}^3\)
- At \(60\text{ s}\): \(39\text{ cm}^3\)
- At \(90\text{ s}\): \(48\text{ cm}^3\)
- At \(120\text{ s}\): \(52\text{ cm}^3\)
- At \(150\text{ s}\): \(52\text{ cm}^3\)

(i) Explain why the volume of gas in the syringe did not change between \(120\text{ s}\) and \(150\text{ s}\). [1]
(ii) Determine which reactant was completely used up by the end of the reaction. Explain your reasoning. [2]

(c) Describe a chemical test to confirm that the gas collected in the syringe is carbon dioxide.
test: .........................................................................................................
result: ...................................................................................................... [2]

(d) The student repeated the experiment using the same mass of calcium carbonate and the same volume and concentration of hydrochloric acid, but at a higher temperature.
(i) State how the rate of reaction at the higher temperature compares to the rate at room temperature. [1]
(ii) Explain, in terms of particles, how increasing the temperature increases the rate of reaction. [2]

A student investigated a solid mixture, solid **X**, which contains two salts.
Solid **X** was dissolved in distilled water to make solution **X**.
Portions of solution **X** were tested. The observations are shown in the table below.

| Test | Observation |
|---|---|
| **Test 1**
To the first portion of solution **X**, a few drops of aqueous sodium hydroxide were added.
Then, an excess of aqueous sodium hydroxide was added. | White precipitate formed.

Precipitate dissolved in excess to form a colorless solution. |
| **Test 2**
To the second portion of solution **X**, a few drops of aqueous ammonia were added.
Then, an excess of aqueous ammonia was added. | White precipitate formed.

Precipitate remained insoluble in excess. |
| **Test 3**
To the third portion of solution **X**, dilute nitric acid and aqueous silver nitrate were added. | Cream precipitate formed. |
| **Test 4**
To the fourth portion of solution **X**, dilute hydrochloric acid and aqueous barium nitrate were added. | No change / colorless solution remained. |

(a) Identify the halide ion present in solid **X**. [1]
(b) Identify the cation that gives the results in Test 1 and Test 2. [1]
(c) Solid **X** also contains another cation. When a small portion of solid **X** is heated in a dry test-tube with aqueous sodium hydroxide, a gas is evolved.
(i) Describe how to test for this gas and state the expected result.
test: .........................................................................................................
result: ...................................................................................................... [2]
(ii) Identify this second cation. [1]
(iii) Identify the gas evolved. [1]

(d) A separate flame test was performed on a sample of solid **X**.
(i) Describe how a flame test is carried out. [3]
(ii) State the expected flame color if calcium ions were present in solid **X**. [1]

A student is provided with a mixture of three solid substances:
- Nickel(II) carbonate (insoluble in water, reacts with dilute sulfuric acid to form soluble nickel(II) sulfate)
- Barium sulfate (insoluble in water, does not react with dilute sulfuric acid)
- Sodium chloride (soluble in water, does not react with dilute sulfuric acid)

Plan an investigation to obtain a pure, dry sample of solid barium sulfate and a pure, dry sample of nickel(II) sulfate-6-water crystals (\(NiSO_4\cdot6H_2O\)) from this mixture.

You are provided with:
- The mixture of the three solids
- Dilute sulfuric acid
- Distilled water
- Common laboratory apparatus

Your plan should include:
- The steps you would take and the order in which you would perform them
- The names of the practical techniques used
- How you would obtain the pure, dry solids. [10]

An eco-friendly solid hand-warmer contains a mixture of iron powder and sodium chloride. When water is added, the iron rusts exothermically in the presence of air. Sodium chloride acts as a catalyst for this process. Plan an investigation to determine how the concentration of sodium chloride solution used affects the maximum temperature change during the reaction. You are provided with: - Iron powder - Sodium chloride solutions of concentrations: 0.5 mol/dm3, 1.0 mol/dm3, 1.5 mol/dm3, 2.0 mol/dm3, 2.5 mol/dm3 - Access to standard laboratory apparatus. Your plan should include: - the apparatus required, - a detailed experimental method, - the variables that must be controlled, - how the results would be processed to draw a conclusion. You may draw a diagram if it helps your explanation.