Heat and Phase Changes in Substances

The video tutorial explains the processes of changing matter, focusing on condensation, freezing, melting, and evaporation. It begins with an introduction to how vapors condense into liquids when cooled, similar to how rain forms. The concept of freezing is illustrated by turning liquid into solid ice. The tutorial then explains how dew forms on grass through condensation. It also covers how heat causes chocolate to melt and clothes to dry through evaporation, emphasizing the role of temperature in these processes.

What happens to water vapor when it touches a cooler surface?

• It evaporates.

• It condenses into liquid.

• It freezes into ice.

• It remains unchanged.

What is the process called when a liquid turns into a solid?

• Freezing

• Condensation

• Evaporation

• Melting

Why do dew drops form on grass in the morning?

• Because the grass is warmer than the air.

• Because the sun is shining.

• Because the air is dry.

• Because the grass is cooler than the air.

What causes chocolate to melt?

• Cold temperature

• Heat

• Condensation

• Freezing

Why should chocolates be kept in the refrigerator?

• To make them taste better.

• To keep them from melting.

• To make them harder.

• To change their color.

What happens to water molecules in clothes on a sunny day?

• They freeze.

• They condense.

• They remain the same.

• They evaporate.

What is the process called when water turns into gas?

• Melting

• Freezing

• Condensation

• Evaporation

How does heat affect the molecules in a substance?

• It makes them move apart.

• It makes them come closer.

• It freezes them.

• It condenses them.

What is the opposite process of freezing?

• Condensation

• Evaporation

• Sublimation

• Melting

What happens to water molecules during evaporation?

• They freeze.

• They move apart.

• They come closer.

• They slow down.