Cooling by Evaporation MCQs Quiz | Class 9
Welcome to the Class IX Science (Code 086) quiz for Unit I: Matter – Its Nature and Behaviour. This quiz focuses on Cooling by Evaporation MCQs Quiz | Class 9 and covers the cooling effect of evaporation along with its daily life applications. Test your understanding, check your score, and download the detailed PDF answer sheet for revision.
Understanding Cooling by Evaporation
Evaporation is a surface phenomenon where liquid particles gain enough kinetic energy to overcome the forces of attraction and escape into the vapor state even below the boiling point. This process requires energy.
How does it cause cooling?
The particles of liquid absorb energy from the surroundings to regain the energy lost during evaporation. This absorption of energy from the surroundings makes the surroundings cold. This is the fundamental principle behind cooling by evaporation.
Daily Life Applications
- Earthen Pots (Matka): Water seeps through the pores of the pot and evaporates. The energy required for evaporation is taken from the water inside the pot, cooling it down.
- Cotton Clothes in Summer: Cotton is a good absorber of water. It absorbs sweat from our body and exposes it to the atmosphere for easy evaporation, which cools our body.
- Acetone on Palm: When acetone (nail polish remover) is put on the palm, it evaporates rapidly by taking heat from the palm, causing a cooling sensation.
- Sprinkling Water on Roofs: After a hot sunny day, people sprinkle water on the roof or open ground because the large latent heat of vaporization of water helps to cool the hot surface.
Key Comparison
| Evaporation | Boiling |
|---|---|
| Surface phenomenon | Bulk phenomenon |
| Occurs at any temperature below boiling point | Occurs at a fixed temperature (Boiling point) |
| Causes cooling | Does not cause cooling |
Extra Practice Questions
- Why does a desert cooler cool better on a hot dry day?
- How does the rate of evaporation change with wind speed?
- Why are we able to sip hot tea faster from a saucer than a cup?
- What is the role of humidity in the rate of evaporation?
- Explain why perspiration cools the body.
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