Cambridge IGCSE Chemistry - 0620 - Core Paper 3 2022 Winter Zone 1

The structures of seven compounds, A, B, C, D, E, F and G, are shown.

Answer the following questions about these structures. Each structure may be used once, more than once or not at all.

(a) State which structure, A, B, C, D, E, F or G, represents:
(i) a compound that contributes to acid rain ............................................................... [1]
(ii) a product of respiration ............................................................... [1]
(iii) a hydrocarbon that decolourises aqueous bromine ............................................................... [1]
(iv) a carboxylic acid ............................................................... [1]
(v) a compound that is the main constituent of natural gas. ............................................................... [1]

(b) Compound C can be produced by cracking the kerosene fraction of petroleum.
(i) State the meaning of the term cracking. ............................................................... [2]
(ii) Complete the chemical equation for the cracking of $C_{13}H_{28}$ to form $C_{8}H_{18}$ and one other hydrocarbon. $$C_{13}H_{28} \to C_{8}H_{18} + ext{.........................}$$ [1]

(a) The table compares the percentage by mass of the elements in the whole Earth and in the Earth's crust.

\begin{array}{|c|c|c|}\hline \text{element} & \text{percentage by mass in the whole Earth} & \text{percentage by mass in the Earth's crust} \\\hline \text{aluminium} & 1.20 & 8.20 \\\hline \text{calcium} & 1.10 & 3.60 \\\hline \text{iron} & 34.60 & 5.00 \\\hline \text{magnesium} & 12.70 & 2.00 \\\hline \text{oxygen} & 29.50 & 46.60 \\\hline \text{silicon} & 15.20 & 29.50 \\\hline \text{sodium} & 0.60 & 2.80 \\\hline \text{titanium} & 0.10 & 0.55 \\\hline \text{other elements} & & 1.75 \\\hline \text{total} & 100.00 & 100.00 \\\hline\end{array}

Answer these questions using only the information in the table.

(i) Deduce the percentage by mass of the other elements in the whole Earth. .......................................................................................................................... [1]

(ii) State which element is present in the whole Earth in the greatest percentage by mass. .......................................................................................................................... [1]

(iii) Give \textbf{two} major differences in the composition of the whole Earth and the Earth's crust.
1 ..........................................................................................................................
............................................................................................................................
2 ..........................................................................................................................
............................................................................................................................ [2]

(b) Complete the diagram to show the electron arrangement in a calcium atom.

[2]

(c) Iron is extracted from iron ore.

(i) Name an ore of iron. .............................................................................................. [1]

(ii) Iron ore contains iron(III) oxide. Iron(III) oxide is reduced by carbon monoxide in a blast furnace. Complete the chemical equation for this reaction.
$$\text{Fe}_2\text{O}_3 + 3\text{CO} \rightarrow ......\text{Fe} + ......\text{CO}_2$$ [2]

(iii) Calcium carbonate is added to the blast furnace, where it undergoes thermal decomposition. Calcium oxide is formed. State the meaning of the term \textit{thermal decomposition}.
...............................................................................................................................
............................................................................................................................... [2]

(iv) Choose the correct statement about the reaction of calcium oxide in the blast furnace.
Tick (✓) one box.
It reacts with carbon monoxide to form slag.
It reacts with carbon to form carbon dioxide and calcium.
It reacts with impurities in the iron ore to form slag.
It catalyses the removal of oxygen from iron(III) oxide. [1]

(v) State \textbf{one} advantage of recycling iron. .............................................................................................................................. [1]

This question is about fuels and energy production.

(a) Name a fuel that is a solid at room temperature.
.................................................................................................................................... [1]

(b) The diagram shows the apparatus used to compare the energy released when 100 cm³ of water is heated by burning different liquid fuels, J, K, L and M.



All conditions are kept the same, apart from the type of fuel and mass of fuel burned.

The results are shown.

[Table_1] fuel | mass of fuel burned / g | increase in temperature / °C
J | 1 | 5
K | 2 | 9
L | 1 | 6
M | 3 | 12

Deduce which fuel, J, K, L or M, releases the most energy per gram.
.................................................................................................................................... [1]

(c) Name the type of chemical reaction that releases heat energy.
.................................................................................................................................... [1]

(d) Name the two products formed when a hydrocarbon fuel undergoes complete combustion.
.......................................................................... and .................................................................... [2]

(e)
(i) Choose from the list the radioactive isotope used as a source of energy.
Draw a circle around your answer.

$$^{27}Al \quad \; ^{23}Na \quad \; ^{16}O \quad \; ^{235}U$$ [1]

(ii) State one other industrial use of radioactive isotopes.
............................................................................................................................. [1]

(a) The table shows some properties of four halogens.

\[\begin{array}{|c|c|c|c|}\hline \text{halogen} & \text{melting point} & \text{boiling point} & \text{density at room temperature} \\ & \text{in °C} & \text{in °C} & \text{and pressure in g/cm}^3 \\ \hline \text{fluorine} & -220 & -188 & \text{..................} \\ \hline \text{chlorine} & \text{..................} & -35 & 0.003 \\ \hline \text{bromine} & -7 & 59 & 3.12 \\ \hline \text{iodine} & 114 & 184 & 4.93 \\ \hline \end{array}\]

(i) Complete the table by predicting:
• the melting point of chlorine
• the density of fluorine at room temperature and pressure. [2]

(ii) Predict the physical state of fluorine at 0°C.
Give a reason for your answer.
.....................................................................................................................................................................
..................................................................................................................................................................... [2]

(b) Fluorine reacts with water to produce hydrogen fluoride and oxygen.

(i) Complete the chemical equation for this reaction.
......F₂ + 2H₂O → ......HF + O₂ [2]

(ii) In this reaction both oxidation and reduction take place.

State the meaning of the term oxidation.
..................................................................................................................................................................... [1]

(c) Bromine is a red-brown liquid.
A drop of liquid bromine is placed in a gas jar.
After 20 minutes the red-brown colour has spread throughout the gas jar.



Explain these observations using the kinetic particle model.
.....................................................................................................................................................................
.....................................................................................................................................................................
.....................................................................................................................................................................
..................................................................................................................................................................... [3]

This question is about compounds of nitrogen.

(a) Fertilisers containing nitrogen are used by farmers to improve crop growth.
Name two other elements found in most fertilisers that improve crop growth.
........................................................ and ........................................................
[2]

(b) Ammonium chloride, $\text{NH}_4\text{Cl}$, reacts with calcium hydroxide.
The products are ammonia, a salt and a liquid that turns anhydrous copper(II) sulfate blue.
Complete the word equation for this reaction.

[2]

(c) Describe a test for chloride ions.
test ....................................................................................................................................................
observations ........................................................................................................................................
[2]

(d) Bacteria in the soil can convert ammonium ions into oxides of nitrogen.
(i) Give one other source of oxides of nitrogen in the air.
..........................................................................................................................................................
[1]

(ii) State one adverse effect of oxides of nitrogen on health.
..........................................................................................................................................................
[1]

(a) Describe the reaction of excess hydrochloric acid with zinc and with zinc oxide. Give the names of the products and any observations.
reaction with zinc
• products
.............................. and ..............................................
• observations
..................................................................................
reaction with zinc oxide
• products
.............................. and ..............................................
• observations
..................................................................................

(b) (i) Small pieces of zinc react with excess hydrochloric acid of different concentrations. The time taken for each reaction to finish is recorded.
The concentrations of each acid are:
• 0.5 mol/dm$^3$
• 1.0 mol/dm$^3$
• 2.0 mol/dm$^3$
All other conditions stay the same.
Complete the table by writing the concentrations in the first column.
[Table_1]


(b) (ii) Describe the effect on the time taken for the reaction to finish when it is carried out at a lower temperature.
All other conditions stay the same.
...................................................................................

(c) Acids react with alkalis.
Choose the pH value which is alkaline.
Draw a circle around your answer.
pH 1 pH 5 pH 7 pH 12

(d) State the colour change when excess hydrochloric acid is added to a solution of methyl orange in alkali.
from ................................................ to .................................................

(e) Soils where crops are grown can become acidic after fertilisers have been spread on the soil.
(i) Explain why controlling soil acidity is important.
.................................................................
(ii) Name a compound used to control soil acidity.
.................................................................

(f) Describe how to prepare pure dry crystals of sodium sulfate from an aqueous solution of sodium sulfate.
...................................................................................

(a) The structure of lactic acid is shown.

(i) On the structure, draw a circle around the alcohol functional group. [1]
(ii) Deduce the formula of lactic acid to show the number of carbon, hydrogen and oxygen atoms. [1]
(b) Ethanol is an alcohol.
(i) Complete the sentence about ethanol using a word from the list.
ethane ethene methane poly(ethene)
Ethanol is manufactured by fermentation or from ..................................... . [1]
(ii) State two conditions needed for fermentation.
1 .........................................................
2 ......................................................... [2]
(iii) Ethanol is used in drinks and as a fuel.
State one other use of ethanol.
......................................................... [1]
(iv) Name one physical property that can be used to determine if a sample of ethanol is pure or impure.
......................................................... [1]
(c) Ethanol and methanol are in the same homologous series.
Explain the meaning of the term homologous series.
......................................................... [2]

This question is about metals.

(a) Nickel is a transition element. Sodium is an element in Group I of the Periodic Table. Nickel has a higher melting and boiling point than sodium.
Give two other ways in which the physical properties of nickel differ from the physical properties of sodium.
1 ..................................................
2 .................................................. [2]

(b) A steel spoon can be electroplated with nickel. The apparatus is shown.

(i) Choose a word from the list which describes the nickel rod. Draw a circle around your answer.
anion anode cathode cation electrolyte [1]
(ii) Describe the observations made during this electroplating at the:
pure nickel rod ..................................................
spoon .................................................. [2]
(iii) State one reason for electroplating an object.
.................................................. [1]

(c) Deduce the number of electrons and neutrons in one atom of the isotope of nickel shown.
$$\phantom{62 \atop 28} \text{Ni}$$
number of electrons ..................................................
number of neutrons .................................................. [2]

(d) A compound of nickel has the formula NiC$_4$O$_4$.
Complete the table to calculate the relative molecular mass of NiC$_4$O$_4$.
[Table_1]
relative molecular mass = ............................... [2]

(e) The table shows the rates of reaction of four metals with steam.
[Table_2]
Put the four metals in order of their reactivity. Put the least reactive metal first.
least reactive .................................................. most reactive
[Table_3] [2]