Cambridge IGCSE Chemistry - 0620 - Supplement Paper 2 2020 Summer Zone 3

A mixture of ice and water is left to stand and the ice melts.
Which row describes what happens as the ice is melting?
[Table_1]

Which piece of apparatus is used to measure 13.7 cm$^3$ of dilute hydrochloric acid?

Chromatography is carried out on a mixture of three substances. The chromatogram is sprayed with a locating agent. The result is shown.
What are possible reasons why the chromatogram shows only two spots?
1. One of the substances in the mixture is insoluble in the solvent.
2. The locating agent did not react with one of the substances in the mixture.
3. Two of the substances in the mixture have the same $R_f$ values.
4. The $R_f$ value of one of the substances is too small.

The structure of an atom of element X is shown.



What is element X?

The electronic structures of two atoms, P and Q, are shown. P and Q combine together to form a compound. What is the type of bonding in the compound and what is the formula of the compound?
type of bonding | formula
A | ionic | PQ
B | ionic | PQ_2
C | covalent | PQ_2
D | covalent | PQ

Caesium is a metal in Group I of the Periodic Table.
Which description of the bonding in caesium is correct?

Why does magnesium oxide, MgO, have a very high melting point?

Aluminium metal reacts with iron(III) oxide to form aluminium oxide and iron.
Which chemical equation for the reaction between aluminium and iron(III) oxide is correct?

The Haber process is a reversible reaction.
$$\text{N}_2(g) + 3\text{H}_2(g) \rightleftharpoons 2\text{NH}_3(g)$$
The reaction has a 30\% yield of ammonia.
Which volume of ammonia gas, NH$_3$, measured at room temperature and pressure, is obtained by reacting 0.75 moles of hydrogen with excess nitrogen?

Which row describes the reactions during the electrolysis of dilute aqueous sodium chloride?
[Table_1]

The electrolysis of aqueous copper(II) sulfate, using inert electrodes, is shown.
Which statement about a reaction at an electrode is correct?

Ethene gas, $\text{C}_2\text{H}_4$, is completely burned in excess oxygen to form carbon dioxide and water.
The equation for this exothermic reaction is shown.
$\text{C}_2\text{H}_4 + 3\text{O}_2 \rightarrow 2\text{CO}_2 + 2\text{H}_2\text{O}$
The table shows the bond energies involved in the reaction.
[Table_1]
What is the total energy change in this reaction?

Which statements about hydrogen fuel cells are correct?
1. Water is formed as the only waste product.
2. Both water and carbon dioxide are formed as waste products.
3. The overall reaction is $2H_2 + O_2 \rightarrow 2H_2O$.
4. The overall reaction is endothermic.

In which tube is a physical change taking place?

A chemical reaction occurs when the reacting particles collide.
Which reaction conditions would produce the greatest rate of particle collisions? [Table_1]

At room temperature, the conversion of nitrogen dioxide, NO\(_2\), into dinitrogen tetroxide, N\(_2\)O\(_4\), is reversible.
2NO\(_2\)(g) \(\rightleftharpoons\) N\(_2\)O\(_4\)(g)
brown gas                       colourless gas

The forward reaction is exothermic.
Which changes cause the equilibrium to shift to the left?
\begin{array}{|c|c|c|} \hline & \text{pressure} & \text{temperature} \\ \hline A & \text{decrease} & \text{decrease} \\ B & \text{decrease} & \text{increase} \\ C & \text{increase} & \text{decrease} \\ D & \text{increase} & \text{increase} \\ \hline \end{array}

The equation for the reaction between zinc and aqueous copper(II) sulfate is shown.
$\text{Zn} + \text{CuSO}_4 \rightarrow \text{ZnSO}_4 + \text{Cu}$
Which statement is correct?

The graph shows how the pH of a solution changes as an acid is added to an alkali.

acid + alkali \rightarrow salt + water

Which letter represents the area of the graph where both acid and salt are present?

Which statement describes a weak acid?

The apparatus shown is used to prepare aqueous copper(II) sulfate.

What are X and Y?

Which two compounds would react together to form the insoluble salt lead(II) chloride?

[Table_1]

The elements in Group I include lithium, sodium and potassium.
Which statements about these elements are correct?
1 Sodium is denser than lithium.
2 Lithium has a lower melting point than potassium.
3 Potassium is a relatively soft metal.
4 Sodium is less reactive than lithium but more reactive than potassium.

The properties of the element titanium, Ti, can be predicted from its position in the Periodic Table. Which row identifies the properties of titanium? [Table_1]

Which statement about the noble gases is correct?

Which property is shown by all metals?

A salt is heated strongly. The only products are a white solid and a colourless gas. What is the salt?

Molten iron from the blast furnace contains impurities.
The process of turning the impure iron into steel involves blowing oxygen into the molten iron and adding calcium oxide.
What are the reasons for blowing in oxygen and adding calcium oxide?

P, Q, R and S are four metals.
P displaces Q from a solution of its sulfate.
Q reacts with hydrochloric acid and can be extracted from its ore using carbon.
R does not react with hydrochloric acid.
The carbonate of S does not decompose when heated strongly.
What is the order of reactivity of the metals, starting with the most reactive?
[Table]

Which substances can be used to detect the presence of water?
1. cobalt(II) chloride
2. copper(II) sulfate
3. litmus
4. methyl orange

Which processes increase the amount of carbon dioxide in the atmosphere?
1. burning ethanol
2. farming cattle
3. growing trees

Hydrogen and nitrogen react to form ammonia in the Haber process.
$N_2 + 3H_2 \rightleftharpoons 2NH_3$
The forward reaction is exothermic.
Which statements about the process are correct?
1. Nitrogen is obtained from the air.
2. Increasing the temperature of the reaction increases the yield of ammonia.
3. Increasing the reaction pressure increases the yield of ammonia.
4. Vanadium(V) oxide is used as a catalyst.

The diagram shows the positions of sacrificial anodes on the steel hull of a yacht.

Which metal is used to make the anodes?

A student suggests three uses of calcium carbonate (limestone).
1  manufacture of cement
2  manufacture of iron
3  treating alkaline soils
Which suggestions are correct?

Which reaction in the Contact process is catalysed by vanadium(V) oxide?

Ethanol is produced by:
1. the catalytic addition of steam to ethene
2. fermentation.
Which statement is correct?

Which statement about a homologous series is correct?

Increasing the number of atoms in one molecule of a hydrocarbon increases the amount of energy released when it burns.
What is the correct order?
[Table_1]

A small quantity of a solid chemical is added to a large excess of aqueous ethanoic acid. No bubbles of gas are seen and the solid dissolves to give a colourless solution. What was the solid chemical?

Alkanes undergo substitution reactions with chlorine in the presence of ultraviolet light.
Which equation shows a reaction of this type?

Which statement about carbohydrates and proteins is correct?