IGCSE Chemistry 0620 Paper 32, Oct/Nov 2025

is used as a lubricant

forms an ion which is present in every dilute acid

is a metal which does not react with steam

is in Period 3 and forms an ion with a charge of 1– when it reacts.

Complete Table 2.1 to show the number of electrons and neutrons in one atom of ${}_{36}^{84}\text{Kr}$. Table 2.1

Krypton is a gas at room temperature and pressure. A sample of krypton is placed in a sealed syringe with a freely moving plunger. Complete Table 2.2 to show the effect, if any, on the volume of krypton when: • the temperature of the krypton is decreased • the pressure of the krypton is increased. Use the words increases, decreases or no change in your answer. Table 2.2

When krypton is cooled, it becomes a liquid. Describe the arrangement of the particles in liquid krypton. Give your answer in terms of particle separation and motion. particle separation .................................................................................................................... ................................................................................................................................................... particle motion .......................................................................................................................... ...................................................................................................................................................

Table 3.1 shows the masses of ions, in mg, present in a $500{\text{ cm}}^3$ sample of contaminated water. Table 3.1 Answer these questions using the information from Table 3.1. Name the negative ion that has the highest concentration.

State the formula of the ammonium ion.

Describe a test to identify the presence of chloride ions, ${\text{Cl}}^{-}$, in a sample of water. test .................................................................................................................................... observations ...................................................................................................................... ...........................................................................................................................................

Calculate the mass of hydrogencarbonate ions, ${\text{HCO}}_3^{-}$, in $200{\text{ cm}}^3$ of the contaminated water. mass = .............................. mg

The water sample is not suitable for use in practical chemistry. Name a process that makes the water suitable for use in practical chemistry.

Water extracted from a river is made suitable for drinking by filtration and then treatment with carbon followed by chlorination. State why carbon is used in the treatment of water.

State why water is chlorinated.

Fig. 3.1 shows the apparatus used to analyse a sample of water containing coloured substances and the results obtained. Name the separation method shown in Fig. 3.1.

Label the solvent front in Fig. 3.1.

Molecules of compound A are found in some plants. Fig. 4.1 shows the displayed formula of a molecule of compound A. Deduce the molecular formula of compound A to show the number of atoms of carbon, hydrogen and oxygen.

On Fig. 4.1, draw a circle around one part of the molecule responsible for the decolourisation of aqueous bromine.

A different molecule found in plants has the molecular formula ${\text{C}}_{10}{\text{H}}_{16}{\text{O}}_2$. Complete Table 4.1 to calculate the relative molecular mass of ${\text{C}}_{10}{\text{H}}_{16}{\text{O}}_2$. Table 4.1 relative molecular mass = ..............................

Petroleum is a fossil fuel. Name one other fossil fuel.

Fig. 4.2 shows the names of some of the fractions obtained from petroleum using a fractionating column. Using only the fractions shown in Fig. 4.2, name the fraction which contains compounds that: have the longest chain length

have the highest volatility

are used for home heating systems.

Table 4.2 shows some properties of hydrocarbons found in fuel for jet engines. Table 4.2 Identify the unsaturated hydrocarbon in Table 4.2.

Explain your answer in (f)(i).

In excess oxygen, decane undergoes complete combustion to produce carbon dioxide and one other product. Identify this other product.

State one adverse effect to the environment of the production of carbon dioxide.

Ethanol can be used to make jet fuel. Draw the displayed formula of ethanol. Show all the atoms and all the bonds.

Ethanol can be manufactured from ethene and one other reactant. Name the other reactant, and state the temperature and pressure used. reactant ................................................... temperature ........................................ °C pressure ........................................... atm

Nitrogen is in Group V of the Periodic Table. Explain why nitrogen is placed in Group V. Give your answer in terms of electronic configuration.

Tellurium is in Group VI of the Periodic Table. Table 5.1 shows the melting point and the boiling point of tellurium. Table 5.1 Use Table 5.1 to deduce the physical state of tellurium at 650°C. Give a reason for your answer. physical state ............................................................................................................................ reason ....................................................................................................................................... ...................................................................................................................................................

Bromine is in Group VII of the Periodic Table. Give the colour and state of bromine at room temperature and pressure. colour ........................................................................................................................................ state ..........................................................................................................................................

When a sample of sodium is added to a large container of cold water, a chemical reaction occurs. Describe what is observed when sodium is added to water.

Complete the word equation for the reaction of sodium with water. sodium + water $\to$ ....................... ....................... + hydrogen

Sodium carbonate reacts with sulfuric acid to form sodium sulfate, carbon dioxide and one other product. Complete the symbol equation for this reaction. ${\text{Na}}_2{\text{CO}}_3+\text{....................}\to {\text{Na}}_2{\text{SO}}_4+{\text{CO}}_2+\text{....................}$

Solid sodium hydroxide is slowly added to distilled water containing a few drops of thymolphthalein and the mixture is stirred. State the colour change observed when sodium hydroxide is added to water containing thymolphthalein. from ............................................................. to .............................................................

Aqueous sodium hydroxide is an alkali. Complete the sentence about an alkali using one of the words from the list. acid base indicator salt An alkali is a soluble .............................. .

Fluorine is in Group VII of the Periodic Table. Fluorine reacts with sodium to form the ionic compound sodium fluoride. Complete the dot-and-cross diagram in Fig. 5.1 for sodium fluoride to show: • the electronic configuration for each ion • the charge on each ion.

Iron is extracted from its ore using carbon in a blast furnace. Aluminium is extracted from its ore using electrolysis. Name the main ore of aluminium.

Explain why aluminium is not extracted from its ore by reduction with carbon. Give your answer in terms of the reactivity series.

An equation for the reduction of iron(III) oxide using carbon is shown. $2{\text{Fe}}_2{\text{O}}_3+3\text{C}\to 4\text{Fe}+3{\text{CO}}_2$ Explain how this equation shows that iron(III) oxide is reduced.

Iron is made into stainless steel. Stainless steel is an alloy that resists rusting. State what is meant by the term alloy.

Name the two substances required for iron to rust. ............................................................... and ...............................................................

State the chemical name for rust.

Table 6.1 shows the observations when four different metals are added separately to dilute hydrochloric acid. Table 6.1 Put the four metals in order of their reactivity. Put the least reactive metal first. least reactive $⟶$ most reactive

Complete the word equation for the reaction of strontium with hydrochloric acid. strontium + hydrochloric acid $\to$ ....................... ....................... + .......................

Name the process shown in Fig. 7.1.

Label the electrolyte in Fig. 7.1.

Name the product formed at the anode.

The electrodes are made of platinum. State one property of platinum that makes it suitable for use as an electrode.

Suggest a non-metal that could be used as the electrodes.

State whether the process shown in Fig. 7.1 produces a physical or chemical change. Explain your answer. type of change .......................................................................................................................... explanation ............................................................................................................................... ...................................................................................................................................................

Magnesium chloride, ${\text{MgCl}}_2$, exists in different forms. Draw one line from each form of magnesium chloride to its description.

Use Fig. 8.1 to determine the total volume of ${\text{H}}_2\text{S}$ produced when the reaction is complete. total volume of ${\text{H}}_2\text{S}={\text{.............................. cm}}^3$

The reaction is repeated using hydrochloric acid of a higher concentration. All other conditions stay the same. State the effect, if any, on: the time taken for the reaction to finish

the total volume of ${\text{H}}_2\text{S}$ produced when the reaction is complete.

Fig. 8.2 shows the reaction pathway diagram for the reaction of dilute hydrochloric acid with aqueous sodium sulfide. Deduce the type of energy change shown in the diagram in Fig. 8.2. Explain your answer.