IGCSE Chemistry 0620 Paper 42, May/June 2026

Give the symbol of the element from Group I or Group VII which has: atoms with 11 protons

Give the symbol of the element from Group I or Group VII which has: atoms with 35 electrons

Give the symbol of the element from Group I or Group VII which has: molecules with an $M_{\text{r}}$ of 254.

Give the symbol of the element from Group I or Group VII which: is used to detect unsaturated hydrocarbon molecules

Give the symbol of the element from Group I or Group VII which: gives a lilac flame test

Give the symbol of the element from Group I or Group VII which: can displace aqueous bromide ions.

Bonding can be strong or weak. Complete Table 2.1 to describe the strong bonding in the substances shown. Table 2.1

Name the weak attractions that are overcome when bromine boils.

Sodium chloride and silicon(IV) oxide both have a lattice structure. Describe the arrangement of ions in sodium chloride.

Name a substance that has a giant covalent lattice and similar properties to silicon(IV) oxide.

Complete the equation for this reaction. ${\text{ZnCO}}_3+{\text{H}}_2{\text{SO}}_4\to {\text{ZnSO}}_4+\dots \dots \dots \dots \cdots +\dots \dots \dots \dots \dots$

Name one other zinc compound that reacts with dilute sulfuric acid to produce zinc sulfate.

The reaction is complete when no more zinc carbonate dissolves and a white solid of excess zinc carbonate is seen in the reaction mixture. State one other observation which shows the reaction is complete.

$200{\text{ cm}}^3$ of solution A contains $30\text{ g}$ of dissolved ${\text{ZnSO}}_4$. The maximum concentration of ${\text{ZnSO}}_4$ at room temperature is $60\text{ g}$ in $100{\text{ cm}}^3$ of water. State the term used to describe a solution containing the maximum concentration of solute.

Water is allowed to evaporate from solution A. Determine the volume of solution A when ${\text{ZnSO}}_4$ crystals first appear.

Solution B is formed when solution A is evaporated until $20{\text{ cm}}^3$ remains. Calculate the mass of ${\text{ZnSO}}_4$ that is formed from solution B.

Lead(II) sulfate, ${\text{PbSO}}_4$, is an insoluble salt which forms when an aqueous lead(II) salt reacts with an aqueous sulfate salt. Name a lead(II) salt and a sulfate salt that will form lead(II) sulfate. lead(II) salt ........................................................................................................................ sulfate salt .........................................................................................................................

Name this technique of insoluble salt preparation.

Describe how pure lead(II) sulfate can be obtained from the reaction mixture.

Write the ionic equation for this reaction. Include state symbols.

Name another insoluble sulfate salt that can be prepared by this method.

State two physical properties of transition elements that are different from Group I metals. 1 ................................................................................................................................................ 2 ................................................................................................................................................

Write the formulas of the following compounds of transition elements. copper(I) oxide ......................................................................................................................... nickel(II) nitrate ........................................................................................................................

Two ions that contain chromium are chromate(VI) ions, ${\text{CrO}}_4^{2-}$, and dichromate(VI) ions, ${\text{Cr}}_2{\text{O}}_7^{2-}$. ${\text{H}}^{+}(\text{aq})$ ions convert ${\text{CrO}}_4^{2-}(\text{aq})$ ions to ${\text{Cr}}_2{\text{O}}_7^{2-}(\text{aq})$ ions. An equilibrium is reached. $$2{\text{H}}^{+}(\text{aq})+2{\text{CrO}}_4^{2-}(\text{aq})\rightleftharpoons {\text{Cr}}_2{\text{O}}_7^{2-}(\text{aq})+{\text{H}}_2\text{O}(\text{l})$$ Explain why this is not a redox reaction.

Describe this equilibrium in terms of: • the rate of the forward reaction and the rate of the reverse reaction • the concentration of the reactants and of the products.

Explain why increasing the pressure has no effect on the position of equilibrium.

Explain why adding an alkali moves the position of equilibrium to the left.

Transition elements form alloys. Name the alloy which is made by mixing copper with zinc.

Mixing chromium and nickel with iron and a non-metallic element makes a type of steel. Name this type of steel and the non-metallic element used. type of steel ....................................................................................................................... non-metallic element .........................................................................................................

Ammonia is manufactured by reacting hydrogen with nitrogen in the Haber process. State one source of hydrogen and one source of nitrogen. hydrogen ........................................................................................................................... nitrogen .............................................................................................................................

Write the symbol equation for the reaction in the Haber process.

State the typical pressure, in $\text{kPa}$, used in the Haber process.

Aqueous ammonia, ${\text{NH}}_3(\text{aq})$, is used to detect aqueous metal ions. The colour of the precipitate formed when ${\text{NH}}_3(\text{aq})$ is added to an aqueous solution indicates the metal ion present. State the colour and give the name of the precipitate formed when ${\text{NH}}_3(\text{aq})$ is added to ${\text{Cr}}^{3+}(\text{aq})$ ions. colour of precipitate ........................................................................................................... name of precipitate ............................................................................................................

When a few drops of ${\text{NH}}_3(\text{aq})$ are added to ${\text{Zn}}^{2+}(\text{aq})$ a white precipitate forms. When a few drops of ${\text{Zn}}^{2+}(\text{aq})$ are added to ${\text{NH}}_3(\text{aq})$ no precipitate forms. Explain these observations.

The reaction between ammonia and fluorine forms nitrogen trifluoride, ${\text{NF}}_3(\text{g})$, and hydrogen fluoride, $\text{HF}(\text{g})$. $${\text{NH}}_3(\text{g})+3{\text{F}}_2(\text{g})\rightleftharpoons {\text{NF}}_3(\text{g})+3\text{HF}(\text{g})\mathrm{\Delta }H=-870\text{ kJ}\mathrm{/}\text{mol}$$ State how the equation shows this reaction is: exothermic ......................................................................................................................... reversible. ..........................................................................................................................

Figure 5.1 shows an incomplete reaction profile diagram for the forward reaction. On Figure 5.1: • write the formulas of the reactants and the products • draw an arrow, labelled $E_{\text{a}}$, to show the activation energy • draw an arrow, labelled $\mathrm{\Delta }H$, to show the enthalpy change.

The equation for the forward reaction can be represented as shown. Table 5.1 Use the bond energies in Table 5.1 and the $\mathrm{\Delta }H$ value of $-870\text{ kJ}\mathrm{/}\text{mol}$ for the forward reaction to calculate the $\text{H}-\text{F}$ bond energy. Use the following steps. • Calculate the energy needed to break the bonds in the reactants. • Calculate the total energy released when the bonds in the products form. • Calculate the bond energy of the $\text{H}-\text{F}$ bond.

On Figure 5.2, complete the dot-and-cross diagram of a molecule of nitrogen trifluoride.

State why the homologous series of alcohols have similar chemical properties.

Use information from Table 6.1 to answer the following questions. Deduce the number of electrons in a molecule of A.

State the molecular formula of B.

Name C.

Name D.

The structural formula of B, ${\text{CH}}_3{\text{CH}}_2\text{OH}$, can also be written as ${\text{C}}_2{\text{H}}_5\text{OH}$. Explain why the structural formula ${\text{C}}_3{\text{H}}_7\text{OH}$ does not identify C.

Ethanol is a fuel. Write the symbol equation for the complete combustion of ethanol.

Ethanol can be oxidised by two methods. method 1 Heating ethanol with an acidified aqueous oxidising agent. method 2 The oxidation of ethanol using bacteria. Name the acidified aqueous oxidising agent used in method 1.

Give the chemical name of the organic product in method 1.

Name the food product in method 2.

Alcohol D reacts with ethanoic acid in the presence of a catalyst to form ester X and one other product. Draw the displayed formula of ester X.

Name the other product formed.