Change of State: Condensation MCQs Quiz | Class 9
This Class IX Science (Code 086) quiz covers Unit I: Matter – Its Nature and Behaviour, specifically focusing on the topic of Condensation. The questions explore how matter changes state from gas to liquid, real-life examples of condensation, and its relation to cooling. Click Submit to check your answers and download the solution PDF for revision.
Understanding Condensation
Condensation is the process by which a substance changes from its gaseous state to its liquid state. It is the reverse of evaporation. This physical change occurs when particles of a gas lose kinetic energy, typically due to cooling, causing them to move slower and come closer together until the attractive forces pull them into a liquid state.
This process plays a crucial role in the water cycle, leading to the formation of clouds, dew, and fog. It is an exothermic process, meaning it releases heat into the surroundings.
Key Characteristics
- State Change: Gas transforms into Liquid.
- Temperature Relation: Occurs when the temperature drops or pressure increases.
- Energy: Heat energy is released (latent heat of condensation).
- Particle Motion: Particles slow down and intermolecular spaces decrease.
Comparison: Evaporation vs. Condensation
| Feature | Evaporation | Condensation |
|---|---|---|
| Process | Liquid to Gas | Gas to Liquid |
| Thermal Effect | Causes cooling (Endothermic) | Releases heat (Exothermic) |
| Speed | Increases with temperature | Increases with cooling |
Common Examples
- Water Droplets on a Cold Can: Water vapor in the air touches the cold surface, loses heat, and turns into liquid water.
- Fogging of Spectacles: Warm breath hits cold lenses, causing vapor to condense.
- Morning Dew: Vapor condenses on grass when temperatures drop at night.
- Clouds: Water vapor rises, cools at high altitudes, and condenses into tiny droplets.
Extra Practice Questions
- Why do we see steam coming out of our mouth on a cold winter day?
- Is condensation an exothermic or endothermic process? Explain.
- How does pressure affect the condensation point of a gas?
- Name the process responsible for the formation of rain.
- What is the term for gas turning directly into solid without becoming liquid (related concept)?
