IGCSE Chemistry 0620 Paper 32, May/June 2024

Answer the following questions using only the structures in Fig. 1.1. Each structure may be used once, more than once or not at all. State which structure represents: (i) a gas that forms 78% by volume of clean, dry air

a compound with a high melting point

a giant covalent structure

a compound in the same homologous series as ethanol

a product of photosynthesis

a non-metallic element that conducts electricity.

Complete Fig. 1.2 to show the dot-and-cross diagram for structure G. Show the outer electron shells only. Fig. 1.2

Blood plasma is the liquid part of blood. Table 2.1 shows the mass, in mg, of some ions present in $100{\text{ cm}}^3$ of blood plasma. Table 2.1 Answer these questions using information from Table 2.1. (i) Name the positive ion in Table 2.1 that is present in the lowest concentration in blood plasma.

Name the ion in Table 2.1 that contains an element in Group V of the Periodic Table.

Name the compound containing ${\text{Na}}^{+}$ ions and ${\text{SO}}_4^{2-}$ ions.

Describe a test for chloride ions. test ............................................................................................................................................. .................................................................................................................................................... observations .............................................................................................................................. ....................................................................................................................................................

Choose from the list the salt that is insoluble in water. Tick (✓) one box. calcium sulfate magnesium chloride potassium sulfate sodium chloride

Table 2.2 shows some properties of the Group I metals. Table 2.2 Use the information in Table 2.2 to: ● suggest why it is difficult to predict the density of rubidium .................................................................................................................................................... ● describe the observations when sodium reacts with water. ....................................................................................................................................................

State how the melting point of the Group I elements changes down the Group.

Sodium oxide, ${\text{Na}}_2\text{O}$, can be made by heating sodium in a limited supply of oxygen. Complete the symbol equation for this reaction. .....$\text{Na}+{\text{O}}_2\to$ .....${\text{Na}}_2\text{O}$

Label the anode in Fig. 3.1.

Name a non-metal that can be used as the anode.

Name the product formed at each electrode. positive electrode ................................................................................................................ negative electrode ..............................................................................................................

Use your knowledge of the reactivity of magnesium to suggest why an unreactive gas is blown into the electrolysis cell.

Alloys of magnesium and aluminium are used to make aircraft. State the meaning of the term alloy.

Magnesium reacts with hydrochloric acid. (i) Write the formula of the ion that is present in all acids.

Name the gas produced when hydrochloric acid reacts with magnesium.

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

Name the indicator that can be used to determine the pH of a sample of dilute hydrochloric acid.

Draw the displayed formula for a molecule of ethene.

The incomplete combustion of ethene produces a small amount of carbon dioxide. Name two other products of the incomplete combustion of ethene. ................................................................. and ..............................................................

A student extracts a mixture of coloured compounds from a plant. Fig. 4.1 shows the results of chromatography of this mixture. Fig. 4.1 Complete Fig. 4.1, to show: ● where the mixture of coloured compounds is placed on the chromatography paper at the start of the chromatography ● the level of the solvent at the start of the chromatography.

State two characteristics of a mixture. 1 .......................................................................................................................................... ............................................................................................................................................. 2 .......................................................................................................................................... .............................................................................................................................................

An atom of sulfur is represented by the symbol shown. ${}_{16}^{34}\text{S}$ Describe this atom of sulfur in terms of: ● the position of the electrons, neutrons and protons in the atom .................................................................................................................................................... .................................................................................................................................................... ● the number of neutrons and number of protons .................................................................................................................................................... .................................................................................................................................................... ● the electronic configuration. ....................................................................................................................................................

Sulfur burns to produce sulfur dioxide. (i) State one adverse effect of sulfur dioxide in the air.

Complete the symbol equation for the reaction of sulfur dioxide with magnesium. ............. $+2\text{Mg}\to$ .....$\text{MgO}+\text{S}$

Fig. 5.1 shows the displayed formula of a compound of sulfur. Fig. 5.1 Deduce the molecular formula of this compound.

Another compound of sulfur has the formula ${\text{Na}}_2{\text{S}}_2{\text{O}}_7$. Complete Table 5.1 to calculate the relative formula mass of ${\text{Na}}_2{\text{S}}_2{\text{O}}_7$. Table 5.1 relative formula mass = ..............................

Complete the equation by adding the missing state symbols. $2{\text{N}}_2{\text{O}}_5(\text{s})\to 4{\text{NO}}_2$(.....)$ + \text{O}_2$(.....)

Fig. 6.1 shows how the mass of nitrogen pentoxide changes as the reaction proceeds. Fig. 6.1 On Fig. 6.1, draw an X to show where the rate of reaction is fastest.

Deduce the mass of nitrogen pentoxide 12 minutes from the start of the reaction.

At 50°C, the reactant and products are all gases. (i) Describe the effect each of the following has on the rate of decomposition of nitrogen pentoxide. All other conditions stay the same. ● The pressure is decreased. ............................................................................................................................................. ● A catalyst is added to the reaction mixture. .............................................................................................................................................

Increasing the concentration of nitrogen pentoxide increases the rate of decomposition. Choose the correct unit of concentration from the list. Draw a circle around your chosen answer. ${\text{dm}}^3\mathrm{/}\text{g}$ $\text{g}\mathrm{/}\text{dm}$ $\text{g}\mathrm{/}{\text{dm}}^2$ $\text{g}\mathrm{/}{\text{dm}}^3$

Some oxides of nitrogen such as nitrogen dioxide are acidic air pollutants. (i) Choose the pH value which is acidic. Draw a circle around your chosen answer. pH 1 pH 7 pH 8 pH 14

State one way of reducing the emissions of nitrogen dioxide in cars.

Nitrogen dioxide is a yellow liquid which evaporates to form a brown gas at room temperature. A long glass tube is set up as shown in Fig. 6.2. Fig. 6.2 At first, the brown gas can only be seen above the small dish. After a short time, the brown gas has completely filled the tube. Explain these results in terms of kinetic particle theory.

State three other physical properties of iron. 1 ................................................................................................................................................. 2 ................................................................................................................................................. 3 .................................................................................................................................................

Fig. 7.1 shows some clean iron nails placed in four test-tubes, M, N, O and P, under different conditions. Fig. 7.1 State in which test-tube, M, N, O or P, the iron nail is most likely to rust.

Choose from the list the compound in rust. Tick (✓) one box. anhydrous iron(III) oxide anhydrous iron(III) sulfate hydrated iron(III) chloride hydrated iron(III) oxide

Copper is used in electrical wiring because of its good electrical conductivity. State one other reason why copper is used in electrical wiring.

Copper(II) oxide reacts with hydrochloric acid. Complete the word equation for this reaction. copper(II) oxide + hydrochloric acid → ........................ + ........................

Copper can be produced by heating copper(II) oxide in hydrogen. $\text{CuO}+{\text{H}}_2\to \text{Cu}+{\text{H}}_2\text{O}$ Describe how this equation shows that copper(II) oxide is reduced.

The list shows five metals. aluminium copper gold magnesium potassium Put these metals in order of their reactivity. Put the most reactive metal at the top.

Table 8.1 shows the names, formulae and boiling points of some carboxylic acids. Table 8.1 Use the information in Table 8.1 to answer these questions. (i) State the trend in the boiling points of the carboxylic acids.

Deduce the general formula for carboxylic acids.

Complete the word equation for the reaction of ethanoic acid with sodium carbonate. ethanoic acid + sodium carbonate → sodium ethanoate + ........................ + ........................

Choose the correct formula of sodium ethanoate from the list. Draw a circle around your chosen answer. ${\text{CH}}_3{\text{CH}}_2\text{ONa}$ ${\text{CH}}_3{\text{CH}}_2\text{COONa}$ ${\text{CH}}_3\text{COONa}$ $({\text{CH}}_3\text{COO}{)}_2\text{Na}$

Methane, ethane and propane belong to the alkane homologous series. (i) Define the term homologous series.

State the type of bonding in a methane molecule.

State two types of reaction of the alkanes. 1 .......................................................................................................................................... 2 ..........................................................................................................................................