IGCSE Chemistry 0620 Paper 33, May/June 2026

State which substance: is an alkene

reacts with methane in a combustion reaction

is in the same homologous series as ethanol

is a gas that is approximately 21% of clean, dry air

turns damp red litmus paper blue

is in a homologous series with the general formula ${\text{C}}_n{\text{H}}_{2n}$.

State which two substances are hydrocarbons.

Halogens exist as diatomic molecules. Explain what is meant by the term diatomic.

Aqueous bromine reacts with aqueous sodium iodide. Complete the symbol equation for this reaction. $${\text{Br}}_2+2\text{NaI}\to \text{....................}+\text{....................}$$

Identify the type of reaction that takes place when aqueous bromine reacts with aqueous sodium iodide. Draw a circle around your chosen answer. addition displacement neutralisation substitution

Explain why aqueous iodine does not react with aqueous sodium bromide.

Complete Figure 2.1 to show the dot-and-cross diagram for a molecule of fluorine. Show outer shell electrons only.

Fluorine forms fluoride ions. State the electronic configuration of a fluoride ion.

State the meaning of the symbol (aq) in this equation.

Name the salt formed when calcium carbonate reacts with dilute hydrochloric acid.

A student investigates the reaction of large pieces of calcium carbonate with dilute hydrochloric acid. The calcium carbonate is in excess. Figure 3.1 shows how the mass of large pieces of calcium carbonate changes as the reaction proceeds. State why the mass of the reaction mixture decreases.

Deduce the mass of the reaction mixture at $40\text{ s}$. $$\text{mass}=\text{...................................................... g}$$

On Figure 3.1, draw an X to show where the rate of reaction is the fastest.

The student repeats the experiment using the same volume of dilute hydrochloric acid but with smaller pieces of calcium carbonate. Draw a line on the grid in Figure 3.1 to show how the mass of the reaction mixture changes when smaller pieces of calcium carbonate are used.

State how the rate of reaction differs, if at all, when a higher temperature is used.

State how the rate of reaction differs, if at all, when a catalyst is added.

Changing the concentration of a reactant changes the rate of a reaction. Identify the unit of concentration. Draw a circle around your answer. $${\text{mol/dm}}^3{\text{dm}}^3\text{/mol}\text{mol/dm}{\text{dm/mol}}^3$$

Sodium hydroxide is an alkali. State the meaning of the term alkali.

Dilute aqueous sodium hydroxide is added to a solution of thymolphthalein indicator in acid until the sodium hydroxide is in excess. State the colour change seen. from ............................................................. to ............................................................

Predict the boiling point of propane.

Suggest why it is difficult to predict the melting point of butane.

State the trend in the density of the alkanes as the number of carbon atoms increases.

Deduce the physical state of pentane at $-1{}^{\circ }\text{C}$. Give a reason for your answer. physical state .................................................................................................................... reason ............................................................................................................................... ...........................................................................................................................................

Give the general formula for alkanes.

Compound N is unsaturated. Figure 4.1 shows the displayed formula of compound N. On Figure 4.1 draw a circle around the carboxylic acid functional group.

Deduce the molecular formula of compound N.

State why compound N is unsaturated.

Outline how ethanol is manufactured from ethene and steam. In your answer, include: • the name of this reaction • two conditions that are needed. name of reaction ....................................................................................................................... condition 1 ................................................................................................................................ condition 2 ................................................................................................................................

State two general properties of a gas. 1 ................................................................................................................................................ ................................................................................................................................................... 2 ................................................................................................................................................ ...................................................................................................................................................

Complete Table 5.1 to describe the arrangement and motion of particles in a solid and a liquid.

Draw a line from each statement to the correct change of state. statement: liquid oxygen changes into solid oxygen solid copper changes into liquid copper bromine gas changes into liquid bromine change of state: melting condensing freezing

A gas syringe contains $80{\text{ cm}}^3$ of nitrogen gas. State how the volume of nitrogen gas changes, if at all, when the pressure is increased at a constant temperature.

State the period number of titanium in the Periodic Table.

Deduce the number of electrons, neutrons and protons in the titanium ion shown. $${}_{22}^{48}{\text{Ti}}^{2+}$$ number of electrons .......................................................................................................... number of neutrons ........................................................................................................... number of protons .............................................................................................................

Titanium is a transition element. State two properties of transition elements that are different from Group I metals. 1 ................................................................................................................................................ 2 ................................................................................................................................................

Titanium reacts with oxygen to form titanium(III) oxide. Complete the symbol equation for this reaction. $$\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{.}\text{Ti}+\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{.}\mathrm{.}{\text{O}}_2\to 2{\text{Ti}}_2{\text{O}}_3$$

State if titanium(III) oxide is an acidic oxide or a basic oxide. Give a reason for your answer.

Another compound of titanium is titanium(III) chloride. Molten titanium(III) chloride is electrolysed using graphite electrodes. Name the products formed at each electrode during the electrolysis of molten titanium(III) chloride, and give the observations at the positive electrode. product at the negative electrode ............................................................................................. product at the positive electrode ............................................................................................... observations at the positive electrode ...................................................................................... ...................................................................................................................................................

Titanium forms a compound with the nitrate ion. The formula of the compound is $\text{Ti}({\text{NO}}_3{)}_2$. Complete Table 6.1 to calculate the relative formula mass of $\text{Ti}({\text{NO}}_3{)}_2$. relative formula mass = .........................................................

Natural water sources can be polluted with sewage and nitrates. State why sewage and nitrates in river water are harmful. sewage ..................................................................................................................................... ................................................................................................................................................... nitrates ...................................................................................................................................... ...................................................................................................................................................

Some fertilisers contain nitrates. State why fertilisers are used.

Sea water contains sodium ions. Name the test to identify sodium ions. Give the observations for a positive result. test ............................................................................................................................................ observations .............................................................................................................................

The domestic water supply is treated to make it safe to drink. Describe how solids are removed from the domestic water supply.

Name the substance added to the domestic water supply to remove tastes and odours.

State the colour change when water is added to anhydrous copper(II) sulfate. from ................................................................ to ................................................................

Stainless steel is an alloy of iron. Give one reason why alloys are more useful than pure metals.

Brass is an alloy. Name the two metals in brass. ............................................................... and ...............................................................

Five metals are shown. copper gold iron magnesium zinc Put these metals in order of their reactivity. Put the most reactive metal at the top.

Iron is extracted from its ore in a blast furnace. Name the ore used in the blast furnace to extract iron.

State one reason why coke is added to the blast furnace during the extraction process.

Name the compound used to reduce iron(III) oxide in the blast furnace.