Understanding Matter and Phase Changes

A block of ice is left outside on a warm day. After a few hours, it turns into a puddle of water. What phase change has occurred?

• Condensation

• Melting

• Freezing

• Sublimation

When water boils, it turns into steam. Which of the following best explains why the steam is still considered water?

• The steam has a different chemical structure.

• The steam is a different substance.

• The steam is water in a gaseous state.

• The steam is a mixture of water and air.

If you freeze 100 grams of liquid water, what will be the mass of the ice formed?

• 90 grams

• 100 grams

• 110 grams

• 120 grams

A student observes that a puddle of water disappears on a sunny day. Which process is responsible for this observation?

• Freezing

• Condensation

• Evaporation

• Melting

Which of the following statements best describes the conservation of matter during a phase change?

• Matter is destroyed during a phase change.

• Matter is created during a phase change.

• The amount of matter remains the same during a phase change.

• Matter changes into energy during a phase change.

A sealed container has ice and air inside. If the ice melts, what happens to the total mass of the container and its contents?

• The mass decreases.

• The mass increases.

• The mass remains the same.

• The mass becomes zero.

Which of the following best explains why a solid changes to a liquid when heated?

• The particles move slower and stick together.

• The particles move faster and spread apart.

• The particles stop moving.

• The particles change into a different substance.

During the process of condensation, what happens to the energy of the particles in a gas?

• The energy increases.

• The energy decreases.

• The energy remains the same.

• The energy is destroyed.

A student claims that when sugar dissolves in water, it disappears. How would you explain this observation?

• The sugar changes into a gas.

• The sugar is still present but in a dissolved form.

• The sugar is destroyed.

• The sugar changes into water.

Which of the following best describes what happens to the particles of a liquid as it freezes into a solid?

• The particles move faster and spread apart.

• The particles move slower and come closer together.

• The particles stop moving completely.

• The particles change into a different substance.