Matter, Mixtures & Water Properties — Chapter Practice, Grade 6

How can particle models and measurements account for matter across changes? Which parts of a stated sand–salt–water mixture can a filter separate, and where does the matter go?

Problem 1

Does a lower water level prove less water?
Answer and explanation

No. Container shape affects height; compare volume with an appropriate method before claiming loss.

Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.

Problem 2

What mainly changes during gas compression?
Answer and explanation

Particle spacing decreases; the model does not require individual particles to shrink.

Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.

Problem 3

Must water boil before it can evaporate?
Answer and explanation

No. Surface evaporation occurs below boiling; its rate depends on conditions such as temperature, airflow, and exposed area.

Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.

Problem 4

Why is the mass unchanged in this model?
Answer and explanation

The same water remains within the boundary; state and arrangement change, not the amount of matter.

Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.

Problem 5

Develop a complete response: Explain both records using particles and system boundaries. Include relevant evidence and one method or model limit.
Answer and explanation

Melting in the closed sample changes arrangement while retaining its 50 g of water. The open dish loses 6 g from the measured liquid; evaporation is a possible pathway into the air. The water has not been destroyed. Without further records, the mass loss alone does not exclude a spill or specify the evaporation rate over a particular time.

Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.

Problem 6

Apply the unit independently: A learner says a gas has no mass because it cannot be seen. Explain the error. Give a reason and a relevant qualification.
Answer and explanation

Visibility is not the definition of matter. Gas particles have mass and occupy space; a suitable comparison or measurement can show these properties.

Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.

Problem 7

Which statement correctly uses particle model in States of Matter & the Particle Model?
  1. Solid particles are completely motionless.
  2. particle model: A simplified explanation of matter using tiny moving constituents and their arrangement.
  3. A gas has no mass because it is invisible.
  4. One illustrative result establishes every real condition and needs no further evidence.
Answer and explanation

particle model: A simplified explanation of matter using tiny moving constituents and their arrangement.

A simplified explanation of matter using tiny moving constituents and their arrangement. Melting in the closed sample changes arrangement while retaining its 50 g of water. The open dish loses 6 g from the measured liquid; evaporation is a possible pathway into the air. The water has not been destroyed. Without further records, the mass loss alone does not exclude a spill or specify the evaporation rate over a particular time.

Problem 8

Which statement correctly uses evaporation in States of Matter & the Particle Model?
  1. A gas has no mass because it is invisible.
  2. Solid particles are completely motionless.
  3. evaporation: A change from liquid to gas at a surface, possible below boiling.
  4. One illustrative result establishes every real condition and needs no further evidence.
Answer and explanation

evaporation: A change from liquid to gas at a surface, possible below boiling.

A change from liquid to gas at a surface, possible below boiling. Melting in the closed sample changes arrangement while retaining its 50 g of water. The open dish loses 6 g from the measured liquid; evaporation is a possible pathway into the air. The water has not been destroyed. Without further records, the mass loss alone does not exclude a spill or specify the evaporation rate over a particular time.

Problem 9

Why is transparency insufficient for identification?
Answer and explanation

Different substances can share that appearance. Additional appropriate measurements and known source information are needed.

Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.

Problem 10

Does irreversibility alone prove chemical change?
Answer and explanation

No. A physical change can be difficult to undo; evidence about substance identity is more relevant.

Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.

Problem 11

What is the larger piece’s density if it is 60 g and 20 cm³?
Answer and explanation

60 ÷ 20 = 3 g/cm³; size changed but the ratio stayed the same.

Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.

Problem 12

How can a second property strengthen identification?
Answer and explanation

It distinguishes possibilities that the first property cannot separate; the conclusion should still match the available evidence.

Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.

Problem 13

Develop a complete response: Calculate density and explain why the shape change is physical under the stated model. Include relevant evidence and one method or model limit.
Answer and explanation

48 ÷ 24 = 2 g/cm³. Reshaping changes outline while the modeled material and measured mass/volume remain. It is described as physical because no new substance is formed in this model, not simply because the shape might be restored.

Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.

Problem 14

Apply the unit independently: A material is blue and heavy. Can those words uniquely identify it? Give a reason and a relevant qualification.
Answer and explanation

No. Blue depends on the observation conditions, and heavy depends on sample size and comparison. Measured properties and additional evidence are needed.

Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.

Problem 15

Which statement correctly uses physical property in Physical Properties & Physical Changes?
  1. The largest sample must have the greatest density.
  2. Every change that is hard to reverse must be chemical.
  3. physical property: A characteristic measured or observed without changing chemical identity.
  4. One illustrative result establishes every real condition and needs no further evidence.
Answer and explanation

physical property: A characteristic measured or observed without changing chemical identity.

A characteristic measured or observed without changing chemical identity. 48 ÷ 24 = 2 g/cm³. Reshaping changes outline while the modeled material and measured mass/volume remain. It is described as physical because no new substance is formed in this model, not simply because the shape might be restored.

Problem 16

Which statement correctly uses density in Physical Properties & Physical Changes?
  1. One illustrative result establishes every real condition and needs no further evidence.
  2. Every change that is hard to reverse must be chemical.
  3. The largest sample must have the greatest density.
  4. density: Mass per unit volume under stated conditions.
Answer and explanation

density: Mass per unit volume under stated conditions.

Mass per unit volume under stated conditions. 48 ÷ 24 = 2 g/cm³. Reshaping changes outline while the modeled material and measured mass/volume remain. It is described as physical because no new substance is formed in this model, not simply because the shape might be restored.

Problem 17

What does the particle model conserve?
Answer and explanation

The number of each kind of atom. New combinations form, but the represented atoms remain accounted for.

Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.

Problem 18

Do bubbles alone prove a new substance?
Answer and explanation

No. A physical state change can also create bubbles; the gas identity and process need further evidence.

Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.

Problem 19

Was 4 g of matter destroyed?
Answer and explanation

No. It crossed the chosen boundary as gas. The mass inside differs from the mass of the complete accounted system.

Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.

Problem 20

Why does a supplied record still need qualification?
Answer and explanation

The conclusion depends on the record’s stated method and boundaries; illustrative data are not proof that a real procedure was performed.

Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.

Problem 21

Develop a complete response: Explain new combinations and conservation, then distinguish this evidence from color alone. Include relevant evidence and one method or model limit.
Answer and explanation

Two A atoms and two B atoms are represented on each side. Their combinations change from A₂ and B₂ to two AB particles. The closed-system mass remains 60 g. This model directly states a rearrangement; a color change alone would not supply the same evidence of substance identity.

Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.

Problem 22

Apply the unit independently: An exposed metal object gains mass during a stated reaction with oxygen. Does conservation fail? Give a reason and a relevant qualification.
Answer and explanation

No. Oxygen from the surroundings enters the material. Account for both the metal and the added oxygen rather than treating the exposed object as a closed system.

Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.

Problem 23

Which statement correctly uses chemical change in Chemical Changes: Evidence & Conservation?
  1. One illustrative result establishes every real condition and needs no further evidence.
  2. Any bubbles or color change conclusively prove a chemical reaction.
  3. A mass change inside an open container means matter was destroyed.
  4. chemical change: A change that forms substances with different chemical identities.
Answer and explanation

chemical change: A change that forms substances with different chemical identities.

A change that forms substances with different chemical identities. Two A atoms and two B atoms are represented on each side. Their combinations change from A₂ and B₂ to two AB particles. The closed-system mass remains 60 g. This model directly states a rearrangement; a color change alone would not supply the same evidence of substance identity.

Problem 24

Which statement correctly uses conservation of mass in Chemical Changes: Evidence & Conservation?
  1. conservation of mass: Matter remains accounted for when the complete relevant system and exchanges are included.
  2. Any bubbles or color change conclusively prove a chemical reaction.
  3. A mass change inside an open container means matter was destroyed.
  4. One illustrative result establishes every real condition and needs no further evidence.
Answer and explanation

conservation of mass: Matter remains accounted for when the complete relevant system and exchanges are included.

Matter remains accounted for when the complete relevant system and exchanges are included. Two A atoms and two B atoms are represented on each side. Their combinations change from A₂ and B₂ to two AB particles. The closed-system mass remains 60 g. This model directly states a rearrangement; a color change alone would not supply the same evidence of substance identity.

Problem 25

Does dissolved salt disappear as matter?
Answer and explanation

No. Its particles remain in the solution, contributing mass and properties even though they are not individually visible.

Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.

Problem 26

Is the second solution necessarily more concentrated?
Answer and explanation

No. The solute and volume both double, leaving the same ratio under this definition.

Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.

Problem 27

Why is the filtered liquid still a mixture?
Answer and explanation

Dissolved salt passes through with the water. Removing visible sand does not establish pure water.

Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.

Problem 28

Does recovering less sand prove sand was destroyed?
Answer and explanation

No. Identify retained material, loss pathways, and measurement uncertainty before assigning a cause.

Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.

Problem 29

Develop a complete response: Track the substances and mass at each stage, with one limitation. Include relevant evidence and one method or model limit.
Answer and explanation

After removing 3 g sand, 105 g of salt solution remains in the idealized model. After water enters the air, 5 g salt remains. The water is transferred, not destroyed. Real recovery may be incomplete; these assumptions do not show that the liquid was safe to drink.

Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.

Problem 30

Apply the unit independently: A filter removes visible dirt. Does that prove it removes dissolved chemicals or microbes? Give a reason and a relevant qualification.
Answer and explanation

No. Filter pore size and other treatment properties matter. Visible clarity alone cannot establish removal of dissolved substances or drinking safety.

Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.

Problem 31

Which statement correctly uses solution in Mixtures, Solutions & Separation?
  1. solution: A mixture with dissolved particles distributed through a solvent at the particle scale.
  2. A dissolved substance has ceased to exist.
  3. Removing visible particles automatically produces safe pure water.
  4. One illustrative result establishes every real condition and needs no further evidence.
Answer and explanation

solution: A mixture with dissolved particles distributed through a solvent at the particle scale.

A mixture with dissolved particles distributed through a solvent at the particle scale. After removing 3 g sand, 105 g of salt solution remains in the idealized model. After water enters the air, 5 g salt remains. The water is transferred, not destroyed. Real recovery may be incomplete; these assumptions do not show that the liquid was safe to drink.

Problem 32

Which statement correctly uses solute in Mixtures, Solutions & Separation?
  1. A dissolved substance has ceased to exist.
  2. solute: The substance dissolved in a solution.
  3. Removing visible particles automatically produces safe pure water.
  4. One illustrative result establishes every real condition and needs no further evidence.
Answer and explanation

solute: The substance dissolved in a solution.

The substance dissolved in a solution. After removing 3 g sand, 105 g of salt solution remains in the idealized model. After water enters the air, 5 g salt remains. The water is transferred, not destroyed. Real recovery may be incomplete; these assumptions do not show that the liquid was safe to drink.

Problem 33

Which is less dense than the modeled water?
Answer and explanation

The 20 mL object: 12 ÷ 20 = 0.6 g/mL. The second is 2 g/mL; the equal masses do not imply equal floating behavior.

Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.

Problem 34

Why can reshaping affect floating without changing the metal?
Answer and explanation

It changes the object’s geometry and enclosed air, allowing different displacement and average density.

Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.

Problem 35

Did the freezing model lose mass?
Answer and explanation

No. Mass stays 90 g while volume and density change with arrangement.

Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.

Problem 36

Does surface support prove the needle is less dense than water?
Answer and explanation

No. A surface force can matter for a small object; density and buoyancy must be considered separately.

Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.

Problem 37

Develop a complete response: Calculate ice density and explain the hull’s displacement without claiming that every metal floats. Include relevant evidence and one method or model limit.
Answer and explanation

Ice density is 0.9 g/mL. The hull displaces 60 g of modeled water, consistent with buoyancy balancing its weight. A hollow hull can float because of its overall geometry and average density; a compact piece of the same material may behave differently. Neither result is a rule for every temperature or liquid.

Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.

Problem 38

Apply the unit independently: A learner says the largest object must sink first. What measurements would you ask for? Give a reason and a relevant qualification.
Answer and explanation

Ask for mass, volume or displacement, shape, enclosed air, and the liquid’s properties. Size alone does not determine average density or buoyancy.

Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.

Problem 39

Which statement correctly uses buoyancy in Water’s Properties: Density, Floating & Surface Effects?
  1. The heaviest or largest object must always sink.
  2. buoyancy: The upward force a fluid exerts on an immersed or partly immersed object.
  3. Ice floats because freezing removes its mass.
  4. One illustrative result establishes every real condition and needs no further evidence.
Answer and explanation

buoyancy: The upward force a fluid exerts on an immersed or partly immersed object.

The upward force a fluid exerts on an immersed or partly immersed object. Ice density is 0.9 g/mL. The hull displaces 60 g of modeled water, consistent with buoyancy balancing its weight. A hollow hull can float because of its overall geometry and average density; a compact piece of the same material may behave differently. Neither result is a rule for every temperature or liquid.

Problem 40

Which statement correctly uses surface tension in Water’s Properties: Density, Floating & Surface Effects?
  1. Ice floats because freezing removes its mass.
  2. The heaviest or largest object must always sink.
  3. surface tension: An effect of particle interactions at a liquid surface that can influence small surface objects.
  4. One illustrative result establishes every real condition and needs no further evidence.
Answer and explanation

surface tension: An effect of particle interactions at a liquid surface that can influence small surface objects.

An effect of particle interactions at a liquid surface that can influence small surface objects. Ice density is 0.9 g/mL. The hull displaces 60 g of modeled water, consistent with buoyancy balancing its weight. A hollow hull can float because of its overall geometry and average density; a compact piece of the same material may behave differently. Neither result is a rule for every temperature or liquid.

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