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HIA International — Grade 8

Unit 1: Photosynthesis and the carbon cycle

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Unit 2: Properties of materials

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Unit 3: Forces and energy

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Unit 4: Maintaining life

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Unit 5: Reactivity

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Unit 6: Sound and space

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Unit 7: Genes and inheritance

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Unit 8: Rates of reaction

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Unit 9: Electricity

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Quiz

Checkpoint Grade 8 Unit 2 – 2.3 Explaining Changes Of State

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Explaining Changes Of State Checkpoint Chemistry quiz set 2: free practice for Cambridge Checkpoint (chemistry). Work through this Explaining Changes Of State Checkpoint Chemistry quiz set 2 and get instant feedback on every answer. If you get stuck, review the 14.3 Explaining changes of state lesson. More practice: Cambridge Checkpoint (chemistry) — all units. Syllabus: Cambridge Lower Secondary programme.

  • Questions count: 50
  • Passing grade: B+
  • Time limit:
Start Quiz
1.
Which statement correctly describes heat energy?
a force pulling particles toward each other
increase in volume
a model explaining matter using particles
energy transferred because of a temperature difference
2.
Which statement correctly describes attractive force?
energy transferred because of a temperature difference
a model explaining matter using particles
a force pulling particles toward each other
increase in volume
3.
Which statement correctly describes expand?
energy transferred because of a temperature difference
a force pulling particles toward each other
a model explaining matter using particles
increase in volume
4.
Which statement correctly describes particle theory?
energy transferred because of a temperature difference
increase in volume
a model explaining matter using particles
a force pulling particles toward each other
5.
Which of these is the FIRST step in the correct order?
particles move faster
spacing increases
the state may change
energy is transferred to particles
6.
Which step comes immediately after "particles move faster"?
energy is transferred to particles
the state may change
spacing increases
7.
Which practical work belongs to Explaining Changes Of State?
Use observations to classify materials and evaluate a particle model
Measure temperature and volume while heating water and identify patterns in results
Interpret a water-cycle diagram and connect evaporation, condensation, precipitation and run-off
Model particles physically to represent melting, freezing, evaporation and condensation
8.
The diagram shows particles in a beaker of water at 25 °C. The arrows show how fast four particles, P, Q, R and S, are moving. Which particle is most likely to escape as a gas by evaporation in the next instant?
Dr Dabour Hub Academy - figure 1
Particle P
Particle Q
Particle R
Particle S
9.
Divya wrapped two identical flasks of warm water, one in a dry cloth and one in a wet cloth, and left them in a room at 25 °C. Why did the water in the wet-cloth flask end up cooler than the room?
Dr Dabour Hub Academy - figure 2
The wet cloth lets cold water particles soak into the flask
Water in the cloth condenses, which takes energy from the flask
The wet cloth stops any energy reaching the flask from the room
Evaporating water carries energy away from the cloth and flask
10.
The bar chart shows the energy needed to change the state of 1 g of water without changing its temperature. Which explanation of the difference is best?
Dr Dabour Hub Academy - figure 3
Boiling happens at a higher temperature, so the particles must be made larger
Boiling separates particles completely; melting only partly overcomes forces
Melting needs little energy because the forces in ice are stronger than in water
Boiling takes more energy because new particles of steam have to be made
11.
The graph shows a pure substance being heated steadily from -20 °C. In which numbered section are the particles vibrating faster and faster but still held in fixed positions?
Dr Dabour Hub Academy - figure 4
Section 2
Section 3
Section 1
Section 4
12.
In a fume cupboard, a teacher gently heated iodine crystals in a beaker covered by a flask of iced water, as shown. Purple vapour filled the beaker and no liquid was seen. Which statement explains what happens at the bottom of the cold flask?
Dr Dabour Hub Academy - figure 5
Iodine gas particles gain energy there and become large enough to see
The gas particles lose energy and forces hold them as a solid
The iced water melts the iodine, which then drips back into the beaker
Water particles from the flask join with the iodine to form new crystals
13.
Musa heated a beaker of water that was already boiling and recorded its temperature and mass for 10 minutes. The heater supplied energy the whole time. What happened to that energy, according to the particle model?
Dr Dabour Hub Academy - figure 6
It completely overcame the forces, so particles escaped as gas
It made the particles move faster, which is why the temperature went up
It was stored in the beaker, because the temperature did not change
It destroyed water particles, which is why the mass went down
14.
In a hot, dry village, fruit is kept in the pot-in-pot cooler shown. The sand between the pots is kept wet, and the outer clay pot lets water seep through to its outside surface. Why does the fruit stay cool?
Dr Dabour Hub Academy - figure 7
Water vapour condensing on the outer pot takes energy away from the fruit
The wet sand freezes at night and stays frozen during the day
Evaporation from the outer pot takes energy from the fruit
Clay particles stop moving when they are wet, so no energy passes through
15.
Lina used an energy meter while heating 100 g of ice. About how much energy was used only to break the particles out of their fixed positions, without raising the temperature?
About 4 kJ
About 38 kJ
About 50 kJ
About 33 kJ
16.
The higher the temperature needed to melt or boil a substance, the more energy its particles need to overcome their forces of attraction. Using the table, which substance has the weakest forces between its particles?
Iron, because it needs the highest temperature to boil
Oxygen, because very little energy lets its particles separate
Water, because it is a liquid at room temperature
Sodium chloride, because it is a solid at room temperature
17.
Jin kept identical dishes of water at four temperatures in water baths. Which particle explanation fits his results?
At higher temperatures more surface particles have enough energy to escape
At higher temperatures the particles get bigger and are pushed out
At lower temperatures the forces are weaker, so fewer particles escape
Water only evaporates above 40 °C, when the particles start to move
18.
Use the table to link each letter with the name of the change of state. Which pairing is correct?
X – freezing of a liquid
Y – boiling of a liquid
Z – sublimation
Z – melting
19.
A sealed tube of iodine was weighed at three stages. What is the best conclusion from these results?
The iodine particles expanded into gas and then shrank to their normal size
The iodine became lighter as a gas, but the balance was not sensitive enough
Gases have no mass, so the tube must have kept some solid all the time
The particles only spread out and came back together; none were created or destroyed
20.
Chen used a tray of marbles to model changes of state. In his model, what does shaking the tray harder represent, and what do marbles flying out represent?
Making the particles bigger; the liquid freezing
Removing energy; particles condensing into a liquid
Supplying more energy; particles escaping as a gas
Adding more particles; the solid starting to melt
21.
Amira says: "The steam and the boiling water are at the same temperature, so their particles have the same energy." Which is the best evaluation of her claim?
Wrong – the steam has extra energy that was used to overcome the forces
Right – same temperature always means the same energy
Wrong – the boiling water has more energy, because it is a liquid
Right – the particles in steam and water are held by equal forces
22.
Nadia sprays perfume on her wrist and it feels cold as it dries. Which explanation is correct?
Perfume particles condense on the skin and give out energy
The perfume freezes on the skin as the particles slow down
Perfume particles take in energy from the air and become colder
The fastest particles escape, leaving slower ones behind
23.
Ethanol is boiling in a water bath at 78 °C. Although it is still being heated, its temperature stays at 78 °C. Why?
The ethanol has stopped taking in energy from the water bath
The ethanol particles have reached their fastest possible speed
The energy overcomes forces rather than speeding particles up
The thermometer cannot read above the boiling point
24.
Yusuf wants to show that evaporation cools the liquid left behind. Which plan would give the clearest evidence?
Heat a beaker of water and read the thermometer when bubbles appear
Put wet cotton wool on one bulb and dry on another, then compare
Put one thermometer in a freezer and one in a warm room for 5 minutes
Wrap both thermometer bulbs in wet cotton wool and read them after 5 minutes
25.
In a test, Sam wrote: "When chocolate melts, its particles melt and become runny." Which correction is best?
They gain energy and move past each other; they do not melt
The particles do melt, but only the ones on the outside
The particles break into smaller pieces that can flow
The particles lose energy and the forces between them vanish
26.
Why must a gas lose energy before it can condense into a liquid?
Gas particles must shrink before they fit into a liquid
Losing energy makes the particles repel each other
The forces between particles only exist in liquids
Slower particles can be pulled close together by attractive forces
27.
Equal drops of water and of nail varnish remover were placed side by side on a tile at 22 °C. The nail varnish remover evaporated in 2 minutes; the water took 40 minutes. Which particle explanation fits best?
Its particles are larger, so they are pushed out of the liquid
The forces between its particles are weaker, so more can escape
Its particles are colder, so they need no energy to escape
It was boiling, because its bubbles formed all through the drop
28.
Each option pairs a change of state with what happens to the forces between particles. Which pairing is correct?
Boiling – forces become stronger
Melting – forces are partly overcome
Freezing – forces are completely overcome
Condensation – forces vanish for ever
29.
Each option pairs an observation with a particle explanation. Which pairing is correct?
Boiling water staying at 100 °C – energy is used to separate the particles
Mist forming on a cold window – particles gain energy and speed up
Ice melting at 0 °C – particles become too large for fixed positions
A puddle drying on a cool day – slowest particles escape from the surface
30.
Each option pairs an example with a change of state and energy transfer. Which pairing is correct?
Mist on a mirror – evaporation, energy taken in
Water becoming ice at 0 °C – freezing, energy taken in
A puddle drying – boiling, energy given out
Iodine giving purple vapour – sublimation, energy taken in
31.
Which term is described as: energy transferred because of a temperature difference?
attractive force
particle theory
heat energy
expand
32.
Which term is described as: a force pulling particles toward each other?
heat energy
expand
particle theory
attractive force
33.
Which term is described as: increase in volume?
heat energy
attractive force
particle theory
expand
34.
Which term is described as: a model explaining matter using particles?
heat energy
expand
particle theory
attractive force
35.
When a gas condenses, its particles _____, so the forces of attraction can pull them close together.
gain energy and speed up
lose energy and slow down
grow larger and heavier
split into smaller pieces
36.
Hand sanitiser feels cold on the skin because as it evaporates it _____ energy from the skin.
takes in
gives out
destroys
creates new
37.
In boiling, the forces of attraction between the particles are _____ overcome, so the particles move far apart.
only partly
not at all
slightly
completely
38.
The idea that all matter is made of tiny particles that are always moving is called the _____.
law of universal gravitation
theory of evolution
kinetic particle theory
water cycle model
39.
When ice melts, the forces of attraction between its particles are completely overcome. True or false?
True – no forces are left in a liquid
False – they are only partly overcome
True, but only for the particles at the surface
False – the forces become stronger as ice melts
40.
Water left in an open dish in a room is often slightly cooler than the air, because the fastest particles keep leaving. True or false?
False – the water must be the same as the room
False – evaporation warms the liquid left behind
True – evaporation cools the liquid left
True, but only when the water is boiling
41.
When dry ice sublimes, its particles escape from fixed positions straight into a gas, so the forces are completely overcome in one step. True or false?
True – the statement is correct
False – it must melt first, then boil
False – forces are only partly overcome
True, but only in a closed container
42.
As a liquid freezes, its particles slow down and the forces of attraction between them become stronger, holding them in fixed positions. True or false?
False – the forces become weaker as it freezes
False – the particles speed up as it freezes
True, but only if it freezes below 0 °C
True – the statement is correct
43.
According to kinetic particle theory, the particles in a block of metal at -50 °C are completely still. True or false?
True – cold particles cannot move at all
False – the particles are always moving
True, but only for metals, not other solids
False – the particles move past each other freely
44.
The water particles in a pan are the same particles before and after the water boils; only their spacing and movement change. True or false?
False – boiling turns them into air particles
False – boiling makes each particle larger
True – the statement is correct
True, but only if the pan has a lid
45.
While a liquid is boiling, its temperature keeps rising because its particles keep speeding up. True or false?
False – the energy overcomes forces instead
True – more energy always means faster particles
True, but only when heated strongly
False – the particles slow down as it boils
46.
Condensation happens when gas particles gain energy and speed up. True or false?
True – faster particles stick together more
True, but only near a hot surface
False – the particles gain energy and slow down
False – the particles lose energy and slow down
47.
Sweat only cools a runner if it evaporates from the skin; sweat that just drips off does little cooling. True or false?
False – sweat cools the skin because it is cold
True – the cooling comes from evaporation
False – dripping sweat takes the most energy away
True, but only if the sweat is boiling
48.
In a liquid, the forces between particles are strong enough to keep them touching but too weak to hold them in fixed positions. True or false?
False – liquid particles do not touch
False – liquid particles have no forces at all
True – the statement is correct
True, but only for water, not other liquids
49.
Air containing water vapour can be turned into liquid water by cooling it, because slower particles are more easily held together by attractive forces. True or false?
True – the statement is correct
False – cooling makes gas particles spread out
False – water vapour can only become ice
True, but only if the air is also heated
50.
Removing energy from a liquid that is at its freezing point makes its temperature fall straight away. True or false?
True – losing energy always lowers the temperature
True, but only for liquids other than water
False – the temperature rises as it freezes
False – it stays the same until all has frozen
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Part of Unit 2: Properties of materials — see every lesson and quiz in this unit.
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