Matter -3 - Condensation, melting, freezing, sublimation

What is condensation?

• A solid turning into a liquid by absorbing heat.

• A gas turning into a liquid by giving out heat energy.

• A liquid turning into a solid by releasing heat.

• A solid turning directly into a gas.

During condensation, what happens to the kinetic energy of gas particles?

• They gain kinetic energy and speed up.

• Their kinetic energy remains the same.

• They lose kinetic energy and slow down.

• Their kinetic energy transforms into potential energy.

What causes gas particles to be held together during condensation?

• They are pushed together by external pressure.

• The forces of attraction become strong enough as particles lose energy.

• They collide and stick together randomly.

• The temperature increases, forcing them together.

Which of the following is an example of condensation?

• Moth balls having a strong smell.

• The formation of clouds, dew, and fog.

• Solid ice forming from water.

• Wax turning into a liquid at 54°C.

Why does a window get fogged when you blow on it on a cold day?

• The window releases heat, warming the air.

• The water vapor in your warm breath cools and condenses on the cold window.

• The cold glass freezes the air.

• Your breath cleans the dust off the window.

Melting, or fusion, is the change of state from:

• Liquid to solid by releasing heat.

• Solid to liquid by the absorption of heat.

• Gas to liquid by giving out heat.

• Solid to gas without passing through the liquid phase.

What is a "melting point"?

• The temperature at which a liquid starts to boil.

• The temperature at which a substance can exist in all three states.

• The temperature at which a solid changes completely into a liquid.

• The temperature at which a liquid freezes into a solid.

What happens to the temperature of wax while it is actively melting?

• It increases rapidly.

• It decreases slightly.

• It remains constant at its melting point.

• It fluctuates up and down.

According to the document, what is the melting point of wax?

• 0°C

• 100°C

• 54°C

• It varies and is not fixed.

Do all pure substances have the same melting point?

• Yes, all pure substances melt at 100°C.

• Yes, they all have a melting point of 0°C.

• No, different pure substances have different, but fixed, melting points.

• No, the melting point changes based on the volume of the substance.