Cambridge IGCSE Chemistry - 0620 - Supplement Paper 2 2012 Winter Zone 3

‘Particles moving very slowly from an area of high concentration to an area of low concentration.’
Which process is being described above?
A a liquid being frozen
B a solid melting
C a substance diffusing through a liquid
D a substance diffusing through the air

Solid W melts at exactly 54°C and boils at exactly 302°C.
Solid X, when dissolved in water and examined using paper chromatography, shows a blue colour and a red colour.
Which row is correct?
[Table_1]
[Table_1]:
| | contains only | contains more |
| | one substance | than one substance |
| ------------- | -------------- | --------------------- |
| A | W and X | - |
| B | W | X |
| C | X | W |
| D | - | W and X |

Part of the instructions in an experiment reads as follows. Quickly add 50 cm³ of acid. What is the best piece of apparatus to use?
A a burette
B a conical flask
C a measuring cylinder
D a pipette

The nucleon number of an isotope of rubidium is 85.
How many protons, neutrons and electrons are present in an atom of this isotope?
[Table_1]

Which row gives the number of electrons in the outer electron shell of fluorine and of neon?

[Table_1]

| | $^{19}_{9}$F | $^{20}_{10}$Ne |
|---|-------------|----------------|
| A | 7 | 8 |
| B | 7 | 10 |
| C | 9 | 8 |
| D | 9 | 10 |

In the molecules CH₄, HCl and H₂O, which atoms use all of their outer shell electrons in bonding? A. C and Cl B. C and H C. Cl and H D. H and O

The table shows the electronic structures of four atoms.

[Table_1]

Which two atoms combine to form an ionic compound?

A W and X
B W and Y
C X and Y
D X and Z

A compound has the formula CH$_3$CO$_2$H.
How should the relative molecular mass, $M_r$, of this compound be calculated?
A. 12 + 1 + 16
B. 3(12 + 1) + 2(12 + 16) + 1
C. (4 \times 12) + (2 \times 1) + 16
D. (2 \times 12) + (4 \times 1) + (2 \times 16)

In separate experiments, electricity was passed through concentrated aqueous sodium chloride and molten lead bromide.

What would happen in both experiments?

A. A halogen would be formed at the anode.
B. A metal would be formed at the cathode.
C. Hydrogen would be formed at the anode.
D. Hydrogen would be formed at the cathode.

The diagram shows an electrolysis experiment using metals X and Y as electrodes.

One of the metals becomes coated with copper.
Which metal becomes coated and which aqueous solution is used?

metal | aqueous solution
A X | CrCl₃
B X | CuCl₂
C Y | CrCl₃
D Y | CuCl₂

A diagram for the energy change during an exothermic reaction is shown. For which reactions would this be an appropriate diagram? 1 $\text{CH}_4 + 2\text{O}_2 \rightarrow \text{CO}_2 + 2\text{H}_2\text{O}$
2 $2\text{H}_2 + \text{O}_2 \rightarrow 2\text{H}_2\text{O}$
3 $\text{C} + \text{O}_2 \rightarrow \text{CO}_2$ A none of them
B 1 and 2 only
C 2 and 3 only
D all of them

The diagram shows a match.
By striking the match, a chemical reaction takes place.
Which statements about the chemical reaction are correct?
[Table_1]
type of reaction reason
A   endothermic because energy is used to strike the match
B   endothermic because energy is given out as the match burns
C   exothermic because energy is used to strike the match
D   exothermic because energy is given out as the match burns

Solid copper(II) sulfate can exist in two different forms, anhydrous and hydrated.
One of these forms is blue and the other is white.
The change between these two forms is reversible.
blue form ⇌ white form
Which is the blue form and how is the change from the blue form to the white form brought about?

[Table_1]

Table 1:
| blue form | change to white form |
| ----------- | --------------------- |
| A | anhydrous | add water |
| B | anhydrous | heat |
| C | hydrated | add water |
| D | hydrated | heat |

Which statement describes what happens in the reaction shown?
$$2\text{Mg} + \text{CO}_2 \rightarrow 2\text{MgO} + \text{C}$$
A. Carbon and magnesium are both oxidised.
B. Carbon is oxidised and magnesium oxide is reduced.
C. Magnesium is oxidised and carbon dioxide is reduced.
D. Magnesium oxide and carbon dioxide are both reduced.

Which change does not increase the speed of reaction between zinc and hydrochloric acid?
A. adding a catalyst
B. decreasing the particle size of the zinc
C. decreasing the temperature
D. using more concentrated acid

Salts X and Y are separately dissolved in water.
Samples of the solutions obtained are separately tested with dilute hydrochloric acid and with aqueous sodium hydroxide.
In two of the tests, a gaseous product is formed. No precipitate is formed in any of the tests.
What are salts X and Y?

[Table_1]

| | X | Y |
|---|-------|-------|
| A | AgNO₃ | BaSO₄ |
| B | BaSO₄ | Na₂CO₃ |
| C | Na₂CO₃ | NH₄Cl |
| D | NH₄Cl | AgNO₃ |

Some reactions involving sodium are shown.
Which reaction does not involve the formation of a base?

Barium hydroxide is an alkali. It reacts with hydrochloric acid.
How does the pH of the hydrochloric acid change as an excess of aqueous barium hydroxide is added?
A. The pH decreases from 14 and becomes constant at 7.
B. The pH decreases from 14 to about 1.
C. The pH increases from 1 and becomes constant at 7.
D. The pH increases from 1 to about 14.

A compound is a salt if it
A can neutralise an acid.
B contains more than one element.
C dissolves in water.
D is formed when an acid reacts with a base.

The diagram shows an outline of the Periodic Table.
Which ionic compound could be formed?
A. W⁺Y⁻
B. W⁺Z⁻
C. X⁺Y⁻
D. X⁺Z⁻

Element X is in Group VII of the Periodic Table. It reacts with aqueous potassium bromide as shown.
$X_2 + 2KBr \rightarrow 2KX + Br_2$
Which statements about X are correct?
[Table_1]
Table:

The table gives information about four elements.
Which element is a transition metal?

[Table_1]

Why are weather balloons filled with helium rather than hydrogen?

A Helium is found in air.
B Helium is less dense than hydrogen.
C Helium is more dense than hydrogen.
D Helium is unreactive.

The three statements below about aluminium are all correct.
1. Aluminium has an oxide ore.
2. Aluminium is extracted from its ore by electrolysis.
3. Aluminium is used to make cooking utensils.
In which of these statements can 'aluminium' be replaced by 'iron' and still be correct?
[Table_1]

Statement 1: An aluminium alloy containing a small amount of copper is stronger than pure aluminium.

Statement 2: Alloys are made by mixing molten metals together and allowing them to cool.

Which of the following is true?
A Both statements are correct and statement 2 explains statement 1.
B Both statements are correct but statement 2 does not explain statement 1.
C Statement 1 is correct but statement 2 is not correct.
D Statement 2 is correct but statement 1 is not correct.

Iron is extracted from its ore in a Blast Furnace.
Hematite, coke, limestone and hot air are added to the furnace.
Which explanation is not correct?
A. Coke burns and produces a high temperature.
B. Hematite is the ore containing the iron as iron oxide.
C. Hot air provides the oxygen for the burning.
D. Limestone reduces the iron oxide to iron.

How does the reactivity of potassium compare with that of sodium and how does the reactivity of calcium compare with that of magnesium?
[Table_1]

Untreated water can spread diseases such as cholera.
What can be added to drinking water to reduce the spread of such diseases?
A. carbon monoxide
B. chlorine
C. nitrogen monoxide
D. sulfur

Statement 1: The burning of fossil fuels containing sulfur is a cause of 'acid rain'.

Statement 2: Acid rain contains sulfur dioxide which is formed when sulfur compounds burn in the air.

Which of the following is true?
A. Both statements are correct and statement 2 explains statement 1.
B. Both statements are correct, but statement 2 does not explain statement 1.
C. Statement 1 is correct but statement 2 is incorrect.
D. Statement 2 is correct but statement 1 is incorrect.

Argon is a noble gas used to fill light bulbs.
What is the approximate percentage of argon in air?
A 1% B 20% C 79% D 99%

The experiment shown was set up to investigate the rusting of iron.

Rusting occurs in this experiment because of the presence of
A hydrogen and oxygen.
B nitrogen and oxygen.
C nitrogen and water.
D oxygen and water.

What are X and Y in the reaction shown?
ammonium chloride + solution X → alkaline gas Y

[Table_1]
| | X | Y |
|---|---------------------|-----------|
| A | hydrochloric acid | ammonia |
| B | hydrochloric acid | chlorine |
| C | sodium hydroxide | ammonia |
| D | sodium hydroxide | chlorine |

Which process does not produce carbon dioxide?
A. combustion of petrol
B. reaction between an acid and a metal hydroxide
C. reaction between an acid and a carbonate
D. respiration

Two industrial processes that involve heating are:
• extracting iron from its ore using a blast furnace,
• making lime.
In which of these processes is calcium carbonate used?
[Table_1: extracting iron and making lime with ticks and crosses]

Which structure shows a carboxylic acid?
[Image_1: Diagram with labels A, B, C, D showing chemical structures]

Which method is used to obtain petrol from petroleum?
A crystallisation
B diffusion
C filtration
D fractional distillation

Which group of compounds is part of a homologous series?
A. CH4, C2H4, C3H8
B. C3H6, C3H8, C3H7OH
C. CH3OH, C2H5OH, C3H7OH
D. CH3CO2H, CH3CH2OH, HCO2H

Bitumen is a substance obtained from the fractional distillation of petroleum. Which row describes its boiling point and the size of its molecules?

[Table_1: Boiling Point and Size of Molecules]

┌────────────────────────────────────────────────────
│ boiling point │ size of molecules │
├────────────────────────────────────────────────────────────
│ A │ high │ large │
│ B │ high │ small │
│ C │ low │ large │
│ D │ low │ small │
└─────────────────────────────────────────────────────────

A hydrocarbon A is cracked to make B and hydrogen.
Compound C is formed by the addition polymerisation of B.
To which homologous series do A, B and C belong?

[Table_1]

``` \begin{array}{|c|c|c|} \hline & \text{alkene} & \text{alkane} \\ \hline \text{A} & \text{A} & \text{B and C} \\ \hline \text{B} & \text{B} & \text{A and C} \\ \hline \text{C} & \text{C} & \text{A and B} \\ \hline \text{D} & - & \text{A and C} \\ \hline \end{array} ```

Which statement about ethanol is not correct?
A. It can be used as a fuel.
B. It can be used as a solvent.
C. It is formed by reaction between steam and ethane.
D. Its functional group is –OH.