krit.club logo

Air, Water, and Weather - The Water Cycle

Grade 3ICSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

Water exists in three states on Earth: Solid (ice), Liquid (water), and Gas (water vapor). Its chemical notation is H2OH_2O.

Evaporation: This is the process where liquid water from oceans, rivers, and lakes turns into water vapor (gas) due to the heat of the Sun.

Condensation: As water vapor rises higher into the atmosphere, it cools down and turns back into tiny droplets of liquid H2OH_2O. These droplets gather together to form clouds.

Precipitation: When the clouds become too heavy with water droplets, the water falls back to the Earth's surface in the form of rain, snow, or hail.

Collection: The water that falls back to Earth gathers in water bodies like oceans and lakes, or soaks into the ground, starting the cycle again.

The Water Cycle is the continuous movement of water from the Earth to the sky and back again, driven primarily by the Sun's energy.

📐Formulae

H2OH_2O

Freezing Point of Water=0CFreezing \space Point \space of \space Water = 0^\circ C

Boiling Point of Water=100CBoiling \space Point \space of \space Water = 100^\circ C

💡Examples

Problem 1:

Why do wet clothes dry faster on a sunny day than on a cloudy day?

Solution:

Due to a higher rate of Evaporation.

Explanation:

The Sun provides heat energy which turns the liquid H2OH_2O in the clothes into water vapor. On a sunny day, the heat is greater, causing the water molecules to move faster and evaporate more quickly.

Problem 2:

What are the tiny droplets seen on the outside of a cold glass of water called, and how do they form?

Solution:

This is called Condensation.

Explanation:

Water vapor (gas) in the surrounding air touches the cold surface of the glass. This causes the H2OH_2O molecules to lose heat and turn back into liquid droplets.

Problem 3:

Identify the stage of the water cycle when rain falls from the sky.

Solution:

Precipitation.

Explanation:

Precipitation occurs when the clouds can no longer hold the condensed water droplets, and gravity pulls the H2OH_2O back down to the ground.