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Interactive Grade 7 Science Particle Theory & States of Matter Worksheet — Particle Theory & States of Matter Practice

Why does a liquid have a fixed volume but a gas does not, even though both can flow?

A.Liquids are heavier than gases, so gravity gives them a fixed volumeB.In liquids, particles are close enough for attractive forces to keep a fixed number of particles together; in gases, the forces are too weak to do thisC.Liquids are made of larger particles than gases, so they take up more spaceD.Gas particles are lighter than liquid particles, so they float away and have no fixed volume

A student measures the temperature of a boiling liquid. She keeps adding heat but the thermometer reading stays the same. What is the best particle theory explanation for this?

A.The thermometer is broken and cannot measure high temperaturesB.The energy is being used to break the forces between particles rather than increasing their speedC.The particles stop moving during boilingD.The heat energy is being converted to light energy

What is the key difference between evaporation and boiling?

A.Evaporation only happens in gases; boiling happens in liquidsB.Evaporation occurs at the surface of a liquid at any temperature; boiling occurs throughout the liquid at a specific temperatureC.Evaporation requires more energy than boilingD.Boiling can occur below the boiling point but evaporation cannot

Which of the following correctly describes what happens to the particles of a substance at its melting point?

A.Particles gain enough energy to completely separate from each other and move freely in all directionsB.Particles lose energy and slow down to form a regular arrangementC.Particles gain enough energy to break free from their fixed positions but remain close togetherD.Particles change their chemical identity

A substance has a melting point of 1535°C. What does this high melting point suggest about the forces between its particles?

A.The forces between particles are very weak, so little energy is needed to melt itB.The forces between particles are very strong, so a large amount of energy is needed to overcome themC.The substance has very heavy particles that are hard to moveD.The substance must be a gas at room temperature

Two identical glasses are filled with water — one with cold water and one with hot water. A drop of food colouring is added to each. In which glass does the colour spread more quickly, and why?

A.Cold water, because particles are slower and stay in place longerB.Both spread at the same rate because food colouring has its own speedC.Hot water, because particles have more kinetic energy and move faster, spreading the colour more quicklyD.Hot water, because the colour is heavier and sinks faster in hot water

Which of the following correctly describes what happens to the spacing between water molecules when liquid water is heated to become steam?

A.The spacing decreases as molecules are forced closer togetherB.The spacing stays the same but molecules move fasterC.The spacing increases greatly as molecules move far apart from each otherD.The spacing increases slightly but molecules remain close together

A student seals a gas inside a rigid container and then heats it. The pressure inside the container increases. Which particle theory explanation is correct?

A.Heating causes the container to shrink, compressing the gasB.Heating gives particles more kinetic energy so they collide with the container walls more often and with greater forceC.Heating increases the mass of each gas particleD.Heating causes gas particles to stick together, reducing the space between them

A student is comparing the density of a substance in its solid and liquid states. In most substances, the solid is denser than the liquid. Which particle theory idea explains this?

A.Solid particles are larger than liquid particlesB.Solid particles are more tightly packed together, leaving less empty spaceC.Solid particles move faster, so they pack together more tightlyD.Liquid particles repel each other more strongly, pushing them apart

10.

A student notices that sugar dissolves faster in hot water than in cold water. Which particle theory idea best explains this?

A.Hot water has more water molecules than cold waterB.Water molecules in hot water have greater kinetic energy and move faster, colliding with sugar particles more frequentlyC.Sugar particles become smaller when heated, fitting between water molecules more easilyD.Cold water has stronger forces between molecules, repelling sugar particles

11.

Which of the following best describes what 'condensation' is in terms of particle theory?

A.Gas particles slow down, lose kinetic energy, and are pulled together by intermolecular forces to form a liquidB.Gas particles speed up and form a solid instantlyC.Liquid particles gain enough energy to escape and become a gasD.Solid particles absorb energy and move further apart

12.

A student heats ice from -20°C to 120°C. During this process, she plots temperature against time on a graph. Which observation would she make at the two flat sections (plateaus) of the graph?

A.The temperature stops changing because the ice runs out of particlesB.The flat sections occur because energy is being used to change the state of matter, not to raise the temperatureC.The flat sections occur because the ice is cooling down temporarilyD.The flat sections occur because the heating device has stopped working

13.

Which of the following is the best evidence that gases have a very low density compared to liquids and solids?

A.Gases can be lit on fire more easily than liquidsB.A large volume of gas can be compressed into a small container (like a gas cylinder)C.Gases are invisible to the naked eyeD.Gases flow faster than liquids

14.

When a gas is cooled at constant pressure and eventually becomes a liquid, what change occurs in the movement of particles?

A.Particles begin to move faster and further apartB.Particles slow down and are drawn closer together by attractive forcesC.Particles stop moving completelyD.Particles arrange themselves into a regular lattice immediately

15.

In which of the following situations are particles losing energy to their surroundings?

A.A solid melting into a liquidB.A liquid evaporating into a gasC.A gas expanding when heatedD.A gas condensing into a liquid