Important Exam Practice Questions for
IGCSE Chemistry (0620)
Topic: Particulate Nature of Matter
1. The diagram shows an experiment to demonstrate diffusion. [1]
Which statement explains why the ring of ammonium chloride appears as shown?
A Ammonia solution only produces a gas which moves until it meets the hydrochloric acid.
B Both solutions produce a gas, but ammonia moves quicker than hydrogen chloride because it is lighter.
C Hydrochloric acid produces hydrogen chloride which stays at one end of the tube until the ammonia reaches it.
D The two solutions run along the tube until they meet.
2. In which substance are the particles close together and slowly moving past each other? [1]
A air
B ice
C steam
D water
3. A gas jar of bromine vapour and a gas jar of air are set up as shown in diagram 1. The glass slide is removed. Diagram 2 shows the appearance of the gas jars after one hour.
Which statement explains why the bromine and air mix together? [1]
A Bromine is denser than air.
B Bromine is lighter than air.
C Bromine molecules moved upwards and molecules in air moved downwards.
D Molecules in bromine and air moved randomly.
4. Different gases diffuse at different speeds. What is meant by the term diffusion?[1]
5. Different gases diffuse at different speeds. What property of a gas molecule affects the speed at which it diffuses?[1]
6. A crystal of purple potassium manganate(VII) was added to each of the beakers shown in the diagram. [1]
One beaker contained hot water and the other beaker contained cold water. In both beakers the purple colour of the potassium manganate(VII) spreads out. Which result and explanation are correct?
|
|
Result |
Explanation |
|
A |
colour
spreads faster in cold water |
particles
move faster at a higher temperature |
|
B |
colour
spreads faster in cold water |
particles
move slower at a higher temperature |
|
C |
colour
spreads faster in hot water |
particles
move faster at a higher temperature |
|
D |
colour
spreads faster in hot water |
particles
move slower at a higher temperature |
7. A sugar cube is dropped into a hot cup of tea. The tea is not stirred.
Which statement explains why the tea becomes sweet? [1]
A The heated water molecules penetrate the sugar cube.
B The hot tea causes the sugar to melt.
C The sugar cube dissolves and its molecules diffuse.
D The sugar molecules get hot and evaporate.
8. In which process do particles move closer together but remain in motion? [1]
A condensation
B diffusion
C evaporation
D freezing
9. The diagram shows how the molecules in vehicle exhaust gases diffuse into the air.
Which statement describes what happens to these molecules next? [1]
A The molecules fall to the ground because they are heavier than air molecules.
B The molecules go back together as they cool.
C The molecules spread further into the air.
D The molecules stay where they are.
10. The particles of a substance gain energy and change from a regular ordered structure to a disordered structure with large distances between the particles. Which change of state is described? [1]
A boiling
B evaporation
C melting
D sublimation
11. Describe the separation, arrangement and motion of particles of an element in the solid state. [3]
separation ____________
arrangement____________
motion____________
12. Z is a covalent substance. In an experiment, a sample of pure solid Z was continually heated for 11 minutes. The graph shows how the temperature of the sample of pure Z changed during the first 9 minutes.
(a) What is the melting point of pure Z? [1]
(b) The sample of pure Z began to boil at 9 minutes. It was boiled for 2 minutes.
Use this information to sketch on the grid how the temperature of the sample of pure Z changed between 9 minutes and 11 minutes. [1]
(c) The sample of pure Z was continually heated between 2 minutes and 5 minutes. Explain, in terms of attractive forces, why there was no increase in the temperature of the sample of pure Z between 2 minutes and 5 minutes. [2]
(d) Describe how the motion of particles of pure Z changed from 0 minutes to 2 minutes. [2]
Solution
1. (B) Both solutions produce a gas, but ammonia moves quicker than hydrogen chloride because it is lighter.
2. (D) water
3. (D) Molecules in bromine and air moved randomly.
4. Diffusion is the movement of particles spread to fill total available volume, moving from high concentration to low concentration.
5. The speed at which Diffusion of gas molecules depends on Mass/ Relative Mass and temperature of the molecules. More the mass less the speed of diffusion of molecules. More the temperature, more the speed of diffusion of molecules.
6. (C) colour spreads faster in hot water because particles move faster at a higher temperature.
7. (C) The sugar cube dissolves and its molecules diffuse.
8. (A) Condensation
9. (C) The molecules spread further into the air.
10. (D) sublimation
11. separation: touching, arrangement: regular, movement: vibrating
12. a) 80(°C),
b) horizontal line from end of graph at minute 9 to minute 11
c) energy is used to break bonds / overcome attraction between molecules
d) vibrations increase