Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Water exists in three physical states: Solid (ice), Liquid (water), and Gas (water vapour). These states are interconvertible based on temperature changes.
Evaporation is the process by which liquid water turns into water vapour. This happens from the surfaces of oceans, rivers, and lakes when heated by the sun.
Transpiration is a biological process where plants release water vapour into the atmosphere through tiny pores in their leaves called stomata.
Condensation occurs when water vapour in the air cools down and turns back into tiny droplets of liquid water. This process is essential for the formation of clouds.
The Water Cycle (Hydrological Cycle) is the continuous movement of water from the Earth's surface to the atmosphere and back to the Earth through processes like evaporation, transpiration, condensation, and precipitation.
Precipitation happens when water droplets in clouds become too heavy and fall to the Earth as rain, snow, or hail.
Groundwater is the water that seeps through the soil and gets collected above impervious rocks beneath the Earth's surface. It is a major source of fresh water.
Rainwater Harvesting is the technique of collecting and storing rainwater for future use, which helps in recharging the groundwater level.
📐Formulae
💡Examples
Problem 1:
Explain why water droplets appear on the outer surface of a glass tumbler containing ice-cold water.
Solution:
This happens due to the process of condensation.
Explanation:
The air surrounding the glass contains water vapour. When this vapour comes in contact with the cold outer surface of the tumbler, it loses heat and cools down. Consequently, the water vapour converts back into liquid water droplets, which stick to the surface of the glass.
Problem 2:
Calculate the total amount of water collected in a tank if it receives from rain and from a rooftop pipe, but is lost due to a leak.
Solution:
Total water =
Explanation:
We first add the incoming water sources () and then subtract the water lost through the leak ().
Problem 3:
How does the sun play a role in the water cycle?
Solution:
The sun acts as the primary energy source for evaporation.
Explanation:
The heat from the sun increases the kinetic energy of water molecules in water bodies, causing them to escape into the air as water vapour. Without solar energy, the cycle of evaporation and subsequent precipitation would stop.