O Level Chemistry 5070 Paper 11, Oct/Nov 2023

In which changes do the particles move further apart? 1 A gas is heated from $0{}^{\circ }\mathrm{C}$ to $25{}^{\circ }\mathrm{C}$. 2 Pressure is applied to a gas at a constant temperature. 3 Steam condenses to form water. 4 Water evaporates at room temperature. A 1 and 2 B 1 and 4 C 2 and 3 D 3 and 4

Data about two compounds is given. Both compounds have a simple molecular structure.

Two bottles are placed, close together, inside a large container at a temperature of $90{}^{\circ }\mathrm{C}$. One bottle contains $1.0\mathrm{g}$ of ${\mathrm{H}}_2\mathrm{S}$, the other bottle contains $1.0\mathrm{g}$ of $\mathrm{P}\mathrm{C}{\mathrm{l}}_3$. A detector is placed in the container $2.0\mathrm{m}$ away from the two bottles. The two bottles are opened at the same time. Which row is correct?

Substances can be elements, compounds or mixtures. Which row is correct?

The letters X, Y and Z represent different atoms. $${}_{19}^{40}\mathrm{X}{}_{19}^{39}\mathrm{Y}{}_{20}^{40}\mathrm{Z}$$ Which statement is correct? A X and Y are the same element. B X and Z are the same element. C X has more protons than Y. D Z has more neutrons than Y.

A student makes three statements. 1 Calcium ions have a $2+$ charge and oxide ions have a $2-$ charge. 2 Magnesium ions and oxide ions have the same electronic configuration as neon. 3 Calcium ions have three full electron shells and magnesium ions have two full electron shells. Which statements are correct? A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Four statements about graphite, diamond and silicon(IV) oxide are listed. 1 Diamond and silicon(IV) oxide are both very hard and have similar structures. 2 In diamond, each carbon atom is joined to four other carbon atoms. 3 Silicon(IV) oxide forms a giant structure of silicon and oxygen atoms. 4 Diamond and graphite both conduct electricity because they are both forms of carbon. Which statements are correct? A 1, 2 and 3 B 1, 2 and 4 C 1, 3 and 4 D 2, 3 and 4

Which row is correct?

Compound Y is the only substance formed when $500{\mathrm{c}\mathrm{m}}^3$ of ammonia reacts with $250{\mathrm{c}\mathrm{m}}^3$ of carbon dioxide. All measurements are at r.t.p. What is the formula of Y? A $(\mathrm{N}{\mathrm{H}}_4{)}_2\mathrm{C}{\mathrm{O}}_3$ B $\mathrm{N}{\mathrm{H}}_2\mathrm{C}\mathrm{O}\mathrm{O}\mathrm{N}{\mathrm{H}}_4$ C $(\mathrm{N}{\mathrm{H}}_2{)}_2\mathrm{C}\mathrm{O}$ D $\mathrm{N}{\mathrm{H}}_4\mathrm{C}\mathrm{O}\mathrm{O}\mathrm{N}{\mathrm{H}}_4$

How many sodium ions are there in $30\mathrm{g}$ of sodium sulfate? A $1.52\times {10}^{23}$ B $2.54\times {10}^{23}$ C $6.02\times {10}^{23}$ D $1.20\times {10}^{24}$

Three compounds are listed. $$\text{copper(II) nitrate, }\mathrm{C}\mathrm{u}(\mathrm{N}{\mathrm{O}}_3{)}_2$$ $$\text{zinc sulfate, }\mathrm{Z}\mathrm{n}\mathrm{S}{\mathrm{O}}_4$$ $$\text{sodium thiosulfate, }\mathrm{N}{\mathrm{a}}_2{\mathrm{S}}_2{\mathrm{O}}_3$$ Which row shows the element that is present in the greatest percentage by mass in each compound? [relative formula masses, $M_r$: $\mathrm{C}\mathrm{u}(\mathrm{N}{\mathrm{O}}_3{)}_2$, 188; $\mathrm{Z}\mathrm{n}\mathrm{S}{\mathrm{O}}_4$, 161; $\mathrm{N}{\mathrm{a}}_2{\mathrm{S}}_2{\mathrm{O}}_3$, 158]

The complete combustion of $20{\mathrm{c}\mathrm{m}}^3$ of a gaseous alkane, X, requires $130{\mathrm{c}\mathrm{m}}^3$ of oxygen. Both volumes are measured at r.t.p. What could be the identity of X? A butane B ethane C methane D propane

Aqueous copper(II) sulfate is electrolysed with copper electrodes. What is the equation for the reaction occurring at the anode? A $\mathrm{C}\mathrm{u}\to {\mathrm{C}\mathrm{u}}^{2+}+2{\mathrm{e}}^{-}$ B ${\mathrm{C}\mathrm{u}}^{2+}+2{\mathrm{e}}^{-}\to \mathrm{C}\mathrm{u}$ C $4{\mathrm{O}\mathrm{H}}^{-}\to {\mathrm{O}}_2+2{\mathrm{H}}_2\mathrm{O}+4{\mathrm{e}}^{-}$ D $2{\mathrm{S}{\mathrm{O}}_4}^{2-}+2{\mathrm{H}}_2\mathrm{O}\to 2{\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4+{\mathrm{O}}_2+4{\mathrm{e}}^{-}$

Three statements about fuel cells are given. 1 A hydrogen-oxygen fuel cell requires a continuous input of fuel and oxygen. 2 In a hydrogen-oxygen fuel cell, hydrogen is burned in oxygen to produce electricity. 3 When a hydrogen-oxygen fuel cell is operating, water is the only chemical product. Which statements are correct? A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Under certain conditions, nitrogen reacts with oxygen to form ${\mathrm{N}}_2\mathrm{O}$. $$2{\mathrm{N}}_2(\mathrm{g})+{\mathrm{O}}_2(\mathrm{g})\rightleftharpoons 2{\mathrm{N}}_2\mathrm{O}(\mathrm{g})$$ The reaction pathway diagram is shown. What is the activation energy of the reverse reaction? A $-447\mathrm{k}\mathrm{J}\mathrm{/}\mathrm{m}\mathrm{o}\mathrm{l}$ B $-283\mathrm{k}\mathrm{J}\mathrm{/}\mathrm{m}\mathrm{o}\mathrm{l}$ C $+141.5\mathrm{k}\mathrm{J}\mathrm{/}\mathrm{m}\mathrm{o}\mathrm{l}$ D $+283\mathrm{k}\mathrm{J}\mathrm{/}\mathrm{m}\mathrm{o}\mathrm{l}$

Hydrogen and bromine react to form hydrogen bromide. $${\mathrm{H}}_2+\mathrm{B}{\mathrm{r}}_2\to 2\mathrm{H}\mathrm{B}\mathrm{r}$$ Bond energy data is given in the table.

What is the enthalpy change, $\mathrm{\Delta }H$, for this reaction? A $-263\mathrm{k}\mathrm{J}\mathrm{/}\mathrm{m}\mathrm{o}\mathrm{l}$ B $-103\mathrm{k}\mathrm{J}\mathrm{/}\mathrm{m}\mathrm{o}\mathrm{l}$ C $+103\mathrm{k}\mathrm{J}\mathrm{/}\mathrm{m}\mathrm{o}\mathrm{l}$ D $+263\mathrm{k}\mathrm{J}\mathrm{/}\mathrm{m}\mathrm{o}\mathrm{l}$

Octane, ${\mathrm{C}}_8{\mathrm{H}}_{18}$, is a hydrocarbon. When octane is mixed with an excess of oxygen, no change takes place unless energy is supplied. If energy is supplied, in the form of heat or an electric spark, a change takes place quickly. The products of this change include carbon dioxide. Which part of this description shows that the change is a chemical change? A Octane is a hydrocarbon. B No change takes place unless energy is supplied. C The change takes place quickly. D Carbon dioxide is produced.

A student plans to investigate how the rate of the reaction changes when hydrochloric acid and calcium carbonate react. $$\mathrm{C}\mathrm{a}\mathrm{C}{\mathrm{O}}_3(\mathrm{s})+2\mathrm{H}\mathrm{C}\mathrm{l}(\mathrm{a}\mathrm{q})\to \mathrm{C}\mathrm{a}\mathrm{C}{\mathrm{l}}_2(\mathrm{a}\mathrm{q})+{\mathrm{H}}_2\mathrm{O}(\mathrm{l})+\mathrm{C}{\mathrm{O}}_2(\mathrm{g})$$ Three methods are described. 1 Record the mass of the flask and contents every 30 seconds for 5 minutes. 2 Measure and record the volume of gas in the syringe after 30 seconds. 3 Count and record the total number of bubbles of gas in the water every 30 seconds for 5 minutes. Which methods could be used to measure how the rate of reaction changes? A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Aqueous bromine is an equilibrium mixture. $$\mathrm{B}{\mathrm{r}}_2(\mathrm{a}\mathrm{q})+{\mathrm{H}}_2\mathrm{O}(\mathrm{l})\rightleftharpoons \mathrm{O}\mathrm{B}{\mathrm{r}}^{-}(\mathrm{a}\mathrm{q})+\mathrm{B}{\mathrm{r}}^{-}(\mathrm{a}\mathrm{q})+2{\mathrm{H}}^{+}(\mathrm{a}\mathrm{q})$$ Aqueous bromine is orange in colour. The species on the right-hand side of the equation are colourless. Changes are made to three separate portions of the equilibrium mixture. Which row shows how the colour of the mixture changes when a small amount of each substance is added?

In which substance does the nitrogen atom have the same oxidation number as the nitrogen atom in $\mathrm{H}\mathrm{N}{\mathrm{O}}_2$? Assume the following oxidation numbers for the other elements in these compounds: $\mathrm{H},+1$; $\mathrm{F},-1$; $\mathrm{O},-2$. A $\mathrm{N}{\mathrm{F}}_3$ B $\mathrm{N}{\mathrm{H}}_4^{+}$ C $\mathrm{N}\mathrm{O}$ D $\mathrm{N}{\mathrm{O}}_2^{+}$

Limewater is aqueous calcium hydroxide. Which statement about limewater is correct? A It has a pH below 7. B It gives a blue-green colour in the flame test. C It reacts with ammonia to form an ammonium salt. D It turns yellow when methyl orange is added.

Which two oxides will both react with aqueous sodium hydroxide? A calcium oxide and copper(II) oxide B calcium oxide and zinc oxide C copper(II) oxide and sulfur dioxide D sulfur dioxide and zinc oxide

A solution of sodium carbonate is added to tap water. A white precipitate forms. Which ion present in the tap water causes the precipitate to form? A chloride B magnesium C potassium D sulfate

The characteristic properties of elements change from left to right across Period 2 of the Periodic Table. On the left of the period, the charge on the ion formed by an element is: 1 the same as the group number 2 negative. Which statements are correct? A both 1 and 2 B 1 only C 2 only D neither 1 nor 2

Which statement about the Group VII halogens is correct? A Bromine consists of $\mathrm{B}{\mathrm{r}}_2$ molecules at room temperature and pressure. B Iodine will displace bromine from aqueous potassium bromide. C The halogens become darker in colour as the relative molecular mass decreases. D The halogens become more volatile as the relative molecular mass increases.

A power cable requires an element that: 1 conducts electricity 2 has a relatively low density 3 is ductile. Which of these properties does aluminium have? A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Which diagram represents the structure of an alloy? A [Diagram of pure metal atoms arranged in regular rows] B [Diagram of metal lattice containing different-sized atoms] C [Diagram of giant covalent diamond structure] D [Diagram of graphite layered structure]

Most metals react with oxygen in the air to form a metal oxide. Which metal forms a metal oxide layer that reduces its apparent reactivity? A aluminium B copper C iron D silver

Which statement about corrosion of metals is correct? A A barrier method is needed to prevent the corrosion of stainless steel. B Iron corrodes to produce hydrated iron(I) oxide. C Sacrificial protection uses a less reactive metal attached to the metal object that is being protected. D When corrosion occurs, the metal loses electrons to become positive ions.

Some metals and the compounds in their ores are shown.

Which type of reaction occurs in the extraction of each of these metals from its ore? A decomposition by heat B electrolysis C precipitation D reduction

Which statement about natural sources of water and the domestic water supply is correct? A Chlorine is used to remove tastes and odours in the treatment of the domestic water supply. B Metal compounds from detergents can deoxygenate natural sources of water. C Photosynthesis provides the oxygen needed for aquatic life in natural sources of water. D Sedimentation removes nitrates in the treatment of the domestic water supply.

Gases that may be present in the air are listed. 1 neon 2 carbon monoxide 3 nitrogen 4 methane Which gases are atmospheric pollutants? A 1 and 2 B 1 and 3 C 2 and 4 D 3 and 4

Which compounds are in the same homologous series? A $\mathrm{C}{\mathrm{H}}_3\mathrm{C}{\mathrm{H}}_2\mathrm{C}{\mathrm{H}}_2\mathrm{C}{\mathrm{H}}_3$, $\mathrm{C}{\mathrm{H}}_3\mathrm{C}\mathrm{H}\mathrm{C}\mathrm{H}\mathrm{C}{\mathrm{H}}_3$ and $\mathrm{C}{\mathrm{H}}_3\mathrm{C}\mathrm{H}(\mathrm{C}{\mathrm{H}}_3)\mathrm{C}{\mathrm{H}}_3$ B $\mathrm{C}{\mathrm{H}}_2\mathrm{C}\mathrm{H}\mathrm{C}{\mathrm{H}}_3$, $\mathrm{C}{\mathrm{H}}_3\mathrm{C}{\mathrm{H}}_2\mathrm{C}\mathrm{H}\mathrm{C}{\mathrm{H}}_2$ and $\mathrm{C}{\mathrm{H}}_2\mathrm{C}\mathrm{H}\mathrm{C}{\mathrm{H}}_2\mathrm{C}{\mathrm{H}}_3$ C $\mathrm{C}{\mathrm{H}}_3\mathrm{C}\mathrm{H}\mathrm{O}\mathrm{H}\mathrm{C}{\mathrm{H}}_3$, $\mathrm{C}{\mathrm{H}}_3\mathrm{C}{\mathrm{H}}_2\mathrm{C}{\mathrm{H}}_2\mathrm{O}\mathrm{H}$ and $\mathrm{C}{\mathrm{H}}_3\mathrm{C}{\mathrm{H}}_2\mathrm{C}\mathrm{O}\mathrm{O}\mathrm{H}$ D $\mathrm{C}{\mathrm{H}}_3\mathrm{C}{\mathrm{H}}_2\mathrm{C}{\mathrm{H}}_3$, $\mathrm{C}{\mathrm{H}}_3\mathrm{C}{\mathrm{H}}_2\mathrm{C}{\mathrm{H}}_2\mathrm{C}{\mathrm{H}}_3$ and $\mathrm{C}{\mathrm{H}}_2\mathrm{C}\mathrm{H}\mathrm{C}{\mathrm{H}}_2\mathrm{C}{\mathrm{H}}_2\mathrm{C}{\mathrm{H}}_3$

The diagrams show four structures of ${\mathrm{C}}_4{\mathrm{H}}_8$. 1 $\mathrm{C}{\mathrm{H}}_2=\mathrm{C}\mathrm{H}-\mathrm{C}{\mathrm{H}}_2-\mathrm{C}{\mathrm{H}}_3$ 2 $\mathrm{C}{\mathrm{H}}_2=\mathrm{C}(\mathrm{C}{\mathrm{H}}_3)-\mathrm{C}{\mathrm{H}}_3$ 3 $\mathrm{C}{\mathrm{H}}_3-\mathrm{C}\mathrm{H}=\mathrm{C}\mathrm{H}-\mathrm{C}{\mathrm{H}}_3$ 4 $\mathrm{C}{\mathrm{H}}_3-\mathrm{C}(\mathrm{C}{\mathrm{H}}_3)=\mathrm{C}{\mathrm{H}}_2$ Which structures represent the same molecule? A 1 and 2 B 1 and 3 C 2 and 3 D 2 and 4

The displayed formulae of two organic compounds are shown. 1 $\mathrm{C}{\mathrm{H}}_3\mathrm{O}\mathrm{H}$ 2 $\mathrm{H}\mathrm{C}\mathrm{O}\mathrm{O}\mathrm{C}{\mathrm{H}}_2\mathrm{C}{\mathrm{H}}_3$ What are the names of these compounds?

Two products of the separation of petroleum are the lubricating oil fraction and the kerosene / paraffin fraction. Which statement is correct? A The lubricating oil fraction is more viscous than the kerosene / paraffin fraction. B The lubricating oil fraction is more volatile than the kerosene / paraffin fraction. C The lubricating oil fraction has lower boiling points than the kerosene / paraffin fraction. D Molecules in the lubricating oil fraction have smaller chain lengths than molecules in the kerosene / paraffin fraction.

An incomplete equation for the reaction of propane with chlorine is shown. $${\mathrm{C}}_3{\mathrm{H}}_8+\mathrm{C}{\mathrm{l}}_2\to {\mathrm{C}}_3{\mathrm{H}}_7\mathrm{C}\mathrm{l}+\mathrm{X}$$ A student writes three statements about this reaction. 1 The activation energy for this reaction is provided by ultraviolet light. 2 ${\mathrm{C}}_3{\mathrm{H}}_7\mathrm{C}\mathrm{l}$ has two different structural formulae. 3 $\mathrm{X}$ is an acidic gas. Which statements are correct? A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only

Glycerol is an alcohol with three $-\mathrm{O}\mathrm{H}$ groups per molecule. What is the equation for the combustion of glycerol? A ${\mathrm{C}}_3{\mathrm{H}}_8{\mathrm{O}}_3+5{\mathrm{O}}_2\to 3\mathrm{C}{\mathrm{O}}_2+4{\mathrm{H}}_2\mathrm{O}$ B $2{\mathrm{C}}_3{\mathrm{H}}_8{\mathrm{O}}_3+3{\mathrm{O}}_2\to 6\mathrm{C}{\mathrm{O}}_2+8{\mathrm{H}}_2$ C $2{\mathrm{C}}_3{\mathrm{H}}_8{\mathrm{O}}_3+7{\mathrm{O}}_2\to 6\mathrm{C}{\mathrm{O}}_2+8{\mathrm{H}}_2\mathrm{O}$ D $4{\mathrm{C}}_3{\mathrm{H}}_5{\mathrm{O}}_3+11{\mathrm{O}}_2\to 12\mathrm{C}{\mathrm{O}}_2+10{\mathrm{H}}_2\mathrm{O}$

Compound X decolourises acidified aqueous potassium manganate(VII). Compound X has the empirical formula ${\mathrm{C}}_2{\mathrm{H}}_5\mathrm{O}$. Some possible structures of X are shown. 1 $\mathrm{C}{\mathrm{H}}_3\mathrm{C}{\mathrm{H}}_2\mathrm{O}\mathrm{H}$ 2 $\mathrm{H}\mathrm{O}\mathrm{C}{\mathrm{H}}_2\mathrm{C}{\mathrm{H}}_2\mathrm{C}\mathrm{H}(\mathrm{O}\mathrm{H})\mathrm{C}{\mathrm{H}}_3$ 3 $\mathrm{H}\mathrm{O}\mathrm{C}{\mathrm{H}}_2\mathrm{C}{\mathrm{H}}_2\mathrm{C}{\mathrm{H}}_2\mathrm{C}{\mathrm{H}}_2\mathrm{O}\mathrm{H}$ 4 $\mathrm{C}{\mathrm{H}}_3\mathrm{C}{\mathrm{H}}_2\mathrm{C}{\mathrm{H}}_2\mathrm{C}\mathrm{O}\mathrm{O}\mathrm{H}$ Which structures could be correct for compound X? A 1, 2 and 3 B 1 only C 2 and 3 only D 3 and 4

Which statement is correct? A A filtrate is left on the filter paper during filtration. B A saturated solution contains only substances with single bonds. C A solute is a substance that dissolves a solvent. D A solution can never be described as pure.

A student does two experiments. In experiment 1, ammonium carbonate is reacted with dilute hydrochloric acid. In experiment 2, ammonium carbonate is heated with aqueous sodium hydroxide. In each experiment, the gas evolved is tested with damp blue litmus paper and damp red litmus paper. Which row correctly shows the colour of both pieces of litmus paper at the end of each experiment?