IGCSE Chemistry 0620 Paper 22, Oct/Nov 2024

Oxygen melts at $-219{}^{\circ }\mathrm{C}$ and boils at $-183{}^{\circ }\mathrm{C}$. At which temperature is oxygen a liquid? A $-225{}^{\circ }\mathrm{C}$ B $-189{}^{\circ }\mathrm{C}$ C $-175{}^{\circ }\mathrm{C}$ D $25{}^{\circ }\mathrm{C}$

The pressure of a sample of gas is decreased. The temperature is kept constant. Which row describes the effects on the particles?

Rubidium has two isotopes, ${}_{37}^{85}\mathrm{R}\mathrm{b}$ and ${}_{37}^{87}\mathrm{R}\mathrm{b}$. Which statement explains why both isotopes have the same chemical properties? A They have the same number of protons. B They have the same electronic configuration. C They have different numbers of neutrons. D They have different mass numbers.

Which pair of elements react to form a compound with a strong attraction between oppositely charged ions? A carbon and bromine B carbon and nitrogen C sodium and oxygen D sodium and potassium

Four substances, P, Q, R and S, are described. ● P is diatomic. ● Q is a good conductor of electricity when solid and when molten. ● R is a silver solid with a very high melting point. ● S reacts with oxygen to form a brown gas. Which substances are metals? A P and Q B P and S C Q and R D R and S

Which diagram shows the covalent bonding in a molecule of carbon dioxide? A $\mathrm{O}-\mathrm{C}-\mathrm{O}$ B $\mathrm{O}=\mathrm{C}-\mathrm{O}$ C $\mathrm{O}=\mathrm{C}=\mathrm{O}$ D $\mathrm{O}\equiv \mathrm{C}\equiv \mathrm{O}$

The bonding, structure and melting point of sodium chloride and sulfur dichloride are shown.

Why does sulfur dichloride have a lower melting point than sodium chloride? A The covalent bonds in sulfur dichloride are weaker than the attractive forces between molecules in sodium chloride. B The covalent bonds in sulfur dichloride are weaker than the ionic bonds in sodium chloride. C The attractive forces between molecules in sulfur dichloride are weaker than the attractive forces between molecules in sodium chloride. D The attractive forces between molecules in sulfur dichloride are weaker than the ionic bonds in sodium chloride.

Diamond and graphite have giant covalent structures of carbon atoms. Which statement describes graphite? A It has a strong, rigid three-dimensional structure. B It has four strong covalent bonds between each carbon atom. C It has layers, which can slide over each other. D It has no delocalised electrons so does not conduct electricity.

Which row explains the malleability and electrical conductivity of a solid metal?

The equation for the decomposition of ammonium carbonate, $({\mathrm{N}\mathrm{H}}_4{)}_2{\mathrm{C}\mathrm{O}}_3$, is shown. $$({\mathrm{N}\mathrm{H}}_4{)}_2{\mathrm{C}\mathrm{O}}_3(\mathrm{s})\to 2{\mathrm{N}\mathrm{H}}_3(\mathrm{g})+{\mathrm{C}\mathrm{O}}_2(\mathrm{g})+{\mathrm{H}}_2\mathrm{O}(\mathrm{l})$$ [$M_r$: $({\mathrm{N}\mathrm{H}}_4{)}_2{\mathrm{C}\mathrm{O}}_3$, $96$] The total volume of gas produced is $360{\mathrm{c}\mathrm{m}}^3$ at r.t.p. Which mass of ammonium carbonate, $({\mathrm{N}\mathrm{H}}_4{)}_2{\mathrm{C}\mathrm{O}}_3$, is decomposed? A $0.24\mathrm{g}$ B $0.48\mathrm{g}$ C $0.96\mathrm{g}$ D $1.44\mathrm{g}$

What is the empirical formula of a compound that contains $3.66\mathrm{g}$ of hydrogen, $37.8\mathrm{g}$ of phosphorus and $58.5\mathrm{g}$ of oxygen? A ${\mathrm{H}}_6{\mathrm{P}}_2{\mathrm{O}}_6$ B ${\mathrm{H}}_4{\mathrm{P}\mathrm{O}}_4$ C ${\mathrm{H}}_3{\mathrm{P}\mathrm{O}}_3$ D $\mathrm{H}\mathrm{P}\mathrm{O}$

Aqueous copper(II) sulfate is electrolysed using graphite electrodes. Which row identifies the product and observations at each electrode during the electrolysis?

Molten sodium chloride is electrolysed using inert electrodes. Which row shows the products formed at the cathode and anode?

The equation for the formation of ammonia is shown. $${\mathrm{N}}_2+3{\mathrm{H}}_2\to 2{\mathrm{N}\mathrm{H}}_3$$ The reaction pathway diagram for the reaction is shown. [Diagram showing energy vs progress of reaction with activation energy $=+250\mathrm{k}\mathrm{J}\mathrm{/}\mathrm{m}\mathrm{o}\mathrm{l}$, total energy released $=-342\mathrm{k}\mathrm{J}\mathrm{/}\mathrm{m}\mathrm{o}\mathrm{l}$, reactants ${\mathrm{N}}_2+3{\mathrm{H}}_2$, products $2{\mathrm{N}\mathrm{H}}_3$, and enthalpy change] What is the enthalpy change for the reaction? A $-592\mathrm{k}\mathrm{J}\mathrm{/}\mathrm{m}\mathrm{o}\mathrm{l}$ B $-92\mathrm{k}\mathrm{J}\mathrm{/}\mathrm{m}\mathrm{o}\mathrm{l}$ C $+92\mathrm{k}\mathrm{J}\mathrm{/}\mathrm{m}\mathrm{o}\mathrm{l}$ D $+592\mathrm{k}\mathrm{J}\mathrm{/}\mathrm{m}\mathrm{o}\mathrm{l}$

Sulfur dioxide is converted to sulfur trioxide in the Contact process. The conditions used are $450{}^{\circ }\mathrm{C}$ and $200\mathrm{k}\mathrm{P}\mathrm{a}$ with a vanadium(V) oxide catalyst. Which row describes and explains the effect of changing conditions on the rate of reaction?

Hydrogen gas reacts with iodine gas to form hydrogen iodide gas in an equilibrium reaction. $${\mathrm{H}}_2(\mathrm{g})+{\mathrm{I}}_2(\mathrm{g})\rightleftharpoons 2\mathrm{H}\mathrm{I}(\mathrm{g})\mathrm{\Delta }H=+26.5\mathrm{k}\mathrm{J}\mathrm{/}\mathrm{m}\mathrm{o}\mathrm{l}$$ Which changes increase the yield of $\mathrm{H}\mathrm{I}$ at equilibrium? 1 adding a catalyst 2 adding more hydrogen gas 3 increasing the pressure 4 increasing the temperature A 1 and 3 B 1 and 4 C 2 and 3 D 2 and 4

The equation for the reaction of carbon with carbon dioxide is shown. $$\mathrm{C}+{\mathrm{C}\mathrm{O}}_2\to 2\mathrm{C}\mathrm{O}$$ Which row identifies the carbon atom that is reduced and its change in oxidation number?

Aqueous iron(II) sulfate is added to acidified potassium manganate(VII). The purple colour of the potassium manganate(VII) disappears. Aqueous potassium iodide is added to acidified potassium dichromate(VI). A dark brown solution forms. Which row identifies the role of the iron(II) sulfate and the potassium dichromate(VI) in these reactions?

Which row shows the difference between a weak acid and a strong acid?

Which substance turns methyl orange red? A aqueous ammonia B dilute hydrochloric acid C aqueous sodium hydroxide D distilled water

Which row describes zinc oxide and calcium oxide?

Which row shows the properties of a transition element?

Fluorine is the element at the top of Group VII of the Periodic Table. Which statement describes fluorine? A It is inert. B It is monatomic. C It is non-metallic. D It is a solid at room temperature.

When aluminium is placed in dilute hydrochloric acid, there is no reaction. When zinc is placed in dilute hydrochloric acid, bubbles of gas are immediately given off. Which statement correctly explains these observations? A Aluminium is coated with a layer of aluminium oxide. B Aluminium is more reactive than hydrogen. C Aluminium is less reactive than zinc. D Zinc is less reactive than hydrogen.

Which statements about the use of sacrificial protection to prevent iron from rusting are correct? 1 A more reactive metal than iron is used as a sacrificial protector because it undergoes reduction before iron. 2 Zinc is used as a sacrificial protector because it gains electrons more readily than iron. 3 Copper is not used as a sacrificial protector because it is less reactive than iron. 4 Magnesium is used as a sacrificial protector because it loses electrons more readily than iron. A 1 and 2 B 1 and 4 C 2 and 3 D 3 and 4

Aluminium is extracted from its ore by electrolysis. What is the role of cryolite in this process? A to lower the operating temperature B to lower the boiling point of bauxite C to raise the melting point of bauxite D to act as a catalyst

Which row identifies two greenhouse gases and three processes by which they contribute to global warming?

Which mixture contains all of the elements in a typical NPK fertiliser? A ammonium nitrate and calcium phosphate B ammonium phosphate and potassium chloride C potassium nitrate and ammonium chloride D potassium carbonate and ammonium nitrate

Bromine reacts with but-2-ene. What is the displayed formula of the product of this reaction? A [Diagram of $\mathrm{C}{\mathrm{H}}_2\mathrm{B}\mathrm{r}-\mathrm{C}\mathrm{H}\mathrm{B}\mathrm{r}-\mathrm{C}{\mathrm{H}}_2-\mathrm{C}{\mathrm{H}}_3$] B [Diagram of $\mathrm{C}{\mathrm{H}}_3-\mathrm{C}\mathrm{B}{\mathrm{r}}_2-\mathrm{C}{\mathrm{H}}_2-\mathrm{C}{\mathrm{H}}_3$] C [Diagram of $\mathrm{C}{\mathrm{H}}_3-\mathrm{C}\mathrm{H}\mathrm{B}\mathrm{r}-\mathrm{C}\mathrm{H}\mathrm{B}\mathrm{r}-\mathrm{C}{\mathrm{H}}_3$] D [Diagram of $\mathrm{C}{\mathrm{H}}_2\mathrm{B}\mathrm{r}-\mathrm{C}{\mathrm{H}}_2-\mathrm{C}{\mathrm{H}}_2-\mathrm{C}{\mathrm{H}}_2\mathrm{B}\mathrm{r}$]

Which statement is correct? A Bitumen is used as a fuel for ships. B Coal, natural gas and oxygen are all fuels. C Hydrogen is the main constituent of natural gas. D Petroleum is separated into useful substances by fractional distillation.

Which statement explains why ethanoic acid is saturated? A The molecule dissociates completely in water. B There is a carbon–oxygen double bond in the molecule. C The carbon–carbon bond in the molecule is a single bond. D All the carbon–hydrogen bonds in the molecule are single bonds.

Which statement about compounds in the same homologous series is correct? A They have the same chemical properties because they have the same number of carbon atoms. B They have the same physical properties because they have the same number of carbon atoms. C They have different chemical properties because they have different numbers of carbon atoms. D They have different physical properties because they have different numbers of carbon atoms.

Which row shows the properties of methane?

The table shows two methods used to make ethanol.

Which statement gives an advantage of preparing ethanol by fermentation rather than by adding steam to ethene? A Fermentation takes several days to complete. B Little energy is used in the fermentation process. C The fermentation of glucose from sugar cane produces pure ethanol. D Fermentation uses a non-renewable raw material.

Which equation represents an addition reaction? A ${\mathrm{C}\mathrm{H}}_3\mathrm{C}\mathrm{H}\mathrm{O}+\mathrm{H}\mathrm{C}\mathrm{N}\to {\mathrm{C}\mathrm{H}}_3\mathrm{C}\mathrm{H}(\mathrm{O}\mathrm{H})\mathrm{C}\mathrm{N}$ B ${\mathrm{C}}_6{\mathrm{H}}_6+{\mathrm{B}\mathrm{r}}_2\to {\mathrm{C}}_6{\mathrm{H}}_5\mathrm{B}\mathrm{r}+\mathrm{H}\mathrm{B}\mathrm{r}$ C ${\mathrm{N}\mathrm{H}}_4\mathrm{B}\mathrm{r}\to {\mathrm{N}\mathrm{H}}_3+\mathrm{H}\mathrm{B}\mathrm{r}$ D ${\mathrm{C}}_{14}{\mathrm{H}}_{30}\to {\mathrm{C}}_2{\mathrm{H}}_4+{\mathrm{C}}_8{\mathrm{H}}_{18}+{\mathrm{C}}_4{\mathrm{H}}_8$

The structure of part of a polymer is shown. [Diagram of polymer chain showing $-{\mathrm{C}\mathrm{H}}_2-\mathrm{N}\mathrm{H}-\mathrm{C}\mathrm{O}-{\mathrm{C}\mathrm{H}}_2-{\mathrm{C}\mathrm{H}}_2-\mathrm{C}\mathrm{O}-\mathrm{O}-{\mathrm{C}\mathrm{H}}_2-\mathrm{N}\mathrm{H}-\mathrm{C}\mathrm{O}-{\mathrm{C}\mathrm{H}}_2-{\mathrm{C}\mathrm{H}}_2-$] How many amide and ester linkages are included in the structure shown?

Which structure represents part of a protein? A [Diagram of polymer with amide linkage and alternating monomer blocks] B [Diagram of polyester chain] C [Diagram of polyamide chain] D [Diagram of polymer containing ester and amide links]

Which piece of apparatus can only measure a single fixed volume? A a $250{\mathrm{c}\mathrm{m}}^3$ beaker B a $50{\mathrm{c}\mathrm{m}}^3$ burette C a $100{\mathrm{c}\mathrm{m}}^3$ measuring cylinder D a $25{\mathrm{c}\mathrm{m}}^3$ volumetric pipette

Pure solid copper(II) nitrate can be obtained from a mixture of copper(II) nitrate and copper powder. Three stages in the method are listed. $$\begin{array}{rl}{\displaystyle \text{X}}& {\displaystyle \text{add water and stir}}\\ {\displaystyle \text{Y}}& {\displaystyle \text{crystallise}}\\ {\displaystyle \text{Z}}& {\displaystyle \text{filter}}\end{array}$$ After the three stages, the copper(II) nitrate is washed and dried. What is the correct order of stages X, Y and Z to obtain pure solid copper(II) nitrate from the mixture? A $\mathrm{X}\to \mathrm{Y}\to \mathrm{Z}$ B $\mathrm{X}\to \mathrm{Z}\to \mathrm{Y}$ C $\mathrm{Y}\to \mathrm{X}\to \mathrm{Z}$ D $\mathrm{Z}\to \mathrm{X}\to \mathrm{Y}$

Which row describes a test and the observation for aqueous sulfate ions?