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Course: HIA International — Grade 7
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Curriculum

HIA International — Grade 7

Unit 1: Breathing and respiration

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Unit 2: Dissolving, solubility and chromatography

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Unit 3: Forces, motion and pressure

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Unit 4: Ecosystems

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Unit 5: Atoms, purity and climate

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Unit 6: Light and objects in space

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Unit 7: Nutrition, health and movement

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Unit 8: Energy changes and reactions of metals

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Unit 9: Magnetism and electromagnets

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Quiz

2.1 Dissolving

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Dissolving Checkpoint Chemistry quiz: free practice for Cambridge Checkpoint (chemistry). Work through this Dissolving Checkpoint Chemistry quiz and get instant feedback on every answer. If you get stuck, review the 12.1 Dissolving lesson. More practice: Cambridge Checkpoint (chemistry) — all units. Syllabus: Cambridge Lower Secondary programme.

  • Questions count: 50
  • Passing grade: B+
  • Time limit:
Start Quiz
1.
Kenji weighed a beaker of water, then stirred in 18.6 g of salt until none could be seen, as shown. No liquid was spilled. What should the balance read after the salt has dissolved?
Dr Dabour Hub Academy - figure 1
212.4 grams
193.8 grams
231.0 grams
Between 212.4 and 231.0 grams
2.
Stirring helps a solid dissolve faster because:
Solvent particles reach the solute more often
It removes the solute
It makes particles bigger
It cools the water
3.
Amara and Ben each planned an investigation, as shown in the table. Which is the best evaluation of Ben's plan?
Fair, because he uses the same volume of water every time
Fair, because he tests the same three temperatures as Amara
Not fair: particle size and stirring change as well as temperature
Not fair, because 100 cm³ of water is too much for 5 g of sugar
4.
Chen wants to find out whether stirring affects how quickly jelly cubes dissolve. Which plan is the best?
Stir one cube in hot water and leave another in cold water; time each
Put one cube in water, stir it, and time how long it takes
Put identical cubes in equal volumes of water at the same temperature; stir one, not the other; time each
Stir cubes of different sizes in the same beaker and see which goes first
5.
Four students drew particle models of a beaker of sugar water after stirring until no crystals could be seen. Which drawing, A, B, C or D, is the correct model?
Dr Dabour Hub Academy - figure 2
Drawing A
Drawing B
Drawing C
Drawing D
6.
Rosa timed how long a stock cube took to dissolve in 250 cm³ of water at four temperatures and drew the curve shown. She did not test 50 °C. Use the graph to estimate the time at 50 °C.
Dr Dabour Hub Academy - figure 3
About 190 seconds
About 150 seconds
About 120 seconds
About 250 seconds
7.
A nurse adds sterile water to a vial of powdered medicine and swirls it gently. Why does swirling help?
It makes the powder particles grow larger
It heats the water above its boiling point
It brings fresh water to the powder so it dissolves faster
It changes the powder into a new medicine
8.
Zainab recorded what happened when she stirred five substances into water. Which two substances from the table are insoluble in water?
Baking soda and Epsom salts
Flour and ground pepper
Instant coffee and flour
Ground pepper and instant coffee
9.
Leo put 10 g of rock sugar into each of two beakers of water at 20 °C. He stirred one and left the other. Each minute, he found the mass of sugar still undissolved. Which piece of evidence from the graph best supports "stirring speeds up dissolving"?
Dr Dabour Hub Academy - figure 4
Both beakers started with exactly 10 g of sugar in them
The unstirred sugar was still dissolving at 6 minutes
After 3 minutes, 1 g was left in the stirred beaker but 7 g in the other
The stirred line reaches 0 g, so stirring makes more sugar dissolve
10.
Three groups dissolved copper sulfate in water and weighed the solution. Which is the most likely reason for group 3's result in the table?
Some solution splashed out or some crystals were left behind
Some copper sulfate particles were destroyed as they dissolved
Dissolving always loses mass, so group 3 is the most accurate
The copper sulfate reacted to make a lighter new substance
11.
Omar stirred four solids into separate beakers of water and left them to stand. The diagram shows what he saw. Which beakers contain a solution with all of the solid dissolved?
Dr Dabour Hub Academy - figure 5
B only, as A is coloured
A and B only
A, B and C
C and D only
12.
Each pairing links a key word to an example from a kitchen. Which pairing is correct?
Solvent – the water in a cup of sweet tea
Solute – the water in a glass of salty water
Solution – the sand at the bottom of a bucket
Insoluble – the sugar stirred into hot tea
13.
The liquid that does the dissolving is the:
Solvent
Solute
Residue
Solution
14.
A chef needs 50 g of salt to dissolve in water as quickly as possible to make a brine. Which choice will work fastest?
Rock salt lumps in warm water, not stirred
Fine table salt in cold water, not stirred
Rock salt lumps in cold water, stirred
Fine table salt in warm water, stirred
15.
Each pairing links a way of speeding up dissolving to its particle explanation. Which pairing is correct?
Stirring – makes each solute particle grow larger
Heating – makes the solute particles slow down
Crushing into powder – more surface exposed to solvent particles
Crushing into powder – makes the water particles lighter
16.
After stirring, the sugar in a glass of water can no longer be seen. Why can it not be seen?
Its particles are too tiny to see and are spread between the water particles
It has changed into water particles
It has melted and become a colourless liquid
It has floated up and escaped into the air
17.
Each pairing links an observation made in the laboratory to a conclusion. Which pairing is correct?
Solid still at the bottom after long stirring – the solid is soluble
Liquid cloudy and solid settles – a solution has formed
Solid can no longer be seen – the solid has melted
Liquid clear with no solid left – the solid is soluble
18.
Which practical work belongs to Dissolving?
Plan, measure, tabulate, graph and evaluate an investigation
Use a baseline, suitable solvent and careful measurement to compare inks or dyes
Measure masses/volumes and identify variables affecting the amount dissolved
Compare materials that dissolve in water and record observations systematically
19.
Lina heated a sample of salty water until it was dry, using the apparatus and readings shown. What mass of salt had been dissolved in the water, and what does this show?
Dr Dabour Hub Academy - figure 6
1.4 g, showing the dissolved salt was there all the time
0 g, showing salt is destroyed once it has dissolved
38.6 g, showing the salt evaporated with the water
40.0 g, showing the whole sample was salt
20.
Dissolving a solid happens in five steps. Each pairing gives a step number and what happens. Which pairing is correct?
Step 1 – solute particles spread between solvent particles
Step 3 – solute particles break away from the solid
Step 2 – the solution looks clear
Step 5 – solvent particles first hit the solid
21.
Tom adds two teaspoons of sugar to each of two mugs of tea at the same temperature. He stirs mug X but not mug Y. After one minute, the tea in mug Y tastes sweet only near the bottom. What is the best explanation?
Sugar is insoluble in tea unless the tea is stirred
The sugar in mug Y melted and sank because it is heavier
Stirring adds extra sugar particles to the top of mug X
Without stirring, the dissolved sugar stays near the solid and spreads upward only slowly
22.
A substance that dissolves in a liquid is:
Opaque
Soluble
Magnetic
Insoluble
23.
Priya says: "Salt dissolves faster in hot water because the hot water makes the salt melt." Which is the best response?
Right: dissolving is the same as melting, just in water
Wrong: salt needs far higher temperatures to melt; faster water particles hit it more often
Wrong: salt dissolves more slowly in hot water
Right: the salt melts first and then mixes with the water
24.
A cleaning company tested four stains, P, Q, R and S, with three solvents. A carpet has stains of both Q and R. Using the table, which single solvent would remove both?
Water, as it dissolves the most substances
Propanone, as both Q and R dissolve in it
Ethanol, as it dissolves Q
None of them, since R dissolves in only one
25.
When sugar dissolves in water, the sugar is the:
Residue
Solute
Solvent
Solution
26.
Which term is described as: the substance that the solute dissolves into, such as the water in sugary water?
solvent
opaque
transparent
solute
27.
Which term is described as: what a solution is - two substances mixed but not chemically joined?
solvent
mixture
dissolving
solution
28.
Match the term to its correct meaning: solute
the substance that dissolves, such as the sugar in sugary water
not able to be seen through, which is how you can tell milk is not a solution
what happens when a solute spreads out among the particles of a solvent
the substance that the solute dissolves into, such as the water in sugary water
29.
Which term is described as: a mixture of a solute dissolved in a solvent?
solution
filtration
mixture
simple distillation
30.
A substance that is able to dissolve in a liquid is described as _____ in that liquid.
insoluble (cannot dissolve)
transparent (see-through)
opaque (not see-through)
soluble (able to dissolve)
31.
Salt can be recovered from salt water by evaporating the water, which shows that dissolving is a _____.
chemical reaction
reversible physical change
change that cannot be undone
type of melting
32.
Use the table. To make the salt water, _____ of water must have been used.
300 grams
324 grams
312 grams
288 grams
33.
Iodine dissolved in alcohol is used to clean cuts. In this solution the alcohol is the _____.
solute that dissolves in the iodine
insoluble part of the mixture
solvent that dissolves the iodine
precipitate left at the bottom
34.
Dissolving needs only one substance. - True or false?
True
False
35.
Milk is a solution because it is a liquid. - True or false?
True
False
36.
In a fair test of how temperature affects dissolving time, the mass of solute should be the same each time. True or false?
False – it should rise with temperature
True – it is a control variable
False – only the stirring must stay the same
True, but only at the highest temperature
37.
In hotter water, water particles move faster and hit the solid more often, so it dissolves faster. True or false?
True – this is why heating speeds dissolving
False – heating slows the particles
False – the solid melts, not dissolves
True, but only for sugar
38.
If 5 g of sugar dissolves in 100 g of water, the solution weighs 100 g because the sugar particles fit into the gaps. True or false?
True – the gaps hide the sugar's mass
True, as long as it is stirred
False – the solution weighs 95 g
False – the solution weighs 105 g
39.
Crushing a sugar cube into powder increases the total mass of sugar that can dissolve in a cup of water. True or false?
True – powder always dissolves more
True, but only in cold water
False – powder cannot dissolve at all
False – it only makes it dissolve faster
40.
Cooking oil does not dissolve in water, so it is described as insoluble in water. True or false?
True – it cannot dissolve in water
False – all liquids are soluble in water
False – oil is the solvent in water
True, but only in hot water
41.
A clear liquid in an unlabelled bottle must be pure water. True or false?
True – solutions are always cloudy
True, if it has no colour
False – it could be a solution
False – it must be a melted solid
42.
In a solution the solute dissolves in the solvent. - True or false?
True
False
43.
When a solid dissolves, its particles spread out between the particles of the solvent. True or false?
False – they sink to the bottom
False – they turn into solvent particles
True – they mix evenly with the solvent
True, but only if heated
44.
If a jar of salt solution is left with its lid on for a week, the salt will sink back to the bottom. True or false?
False – it stays evenly spread out
True – solutes always settle over time
True, as the salt is heavier than water
False – the salt slowly disappears
45.
When blue copper sulfate crystals dissolve in water, the solution is blue but still see-through. True or false?
False – solutions are always colourless
True – solutions can be coloured
False – it would be cloudy blue
True, but only in hot water
46.
In a jug of lemon squash made with water, the water is the solute. True or false?
True – water is always the solute
False – the water is the solvent
True, because there is more water
False – the water is the solution
47.
When sugar dissolves, the sugar disappears and no longer exists. - True or false?
True
False
48.
The more solvent you use, the more solute can be dissolved in it. True or false?
False – the amount of solvent has no effect
False – more solvent dissolves less
True, but only for gases
True – more solvent can dissolve more
49.
A substance that does not dissolve in water will not dissolve in any other liquid either. True or false?
True – water dissolves everything that is soluble
True, because insoluble means never dissolving
False – another solvent may dissolve it
False – it will dissolve if you stir enough
50.
Nail polish dissolving in nail polish remover is melting. - True or false?
True
False
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Part of Unit 2: Dissolving, solubility and chromatography — see every lesson and quiz in this unit.
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