This chapter explains that water exists in three different states—solid (ice), liquid (water), and gas (water vapour or steam). The chapter describes the change of state of water due to temperature changes, such as melting (ice to water), evaporation/boiling (water to vapour), condensation (vapour to water), and freezing (water to ice). It introduces the water cycle, which is the continuous movement of water in nature through evaporation, condensation, and precipitation. The chapter also explains that evaporation becomes faster with an increase in temperature, surface area, and wind speed, while condensation leads to the formation of dew, fog, and clouds. Water is shown to play a vital role in weather, climate, and life on Earth. The chapter highlights that human activities like pollution, wastage, and deforestation disturb the natural water cycle, making water conservation essential through methods such as rainwater harvesting, reducing wastage, and reusing water.
Key Points
Water exists in three states –
– Solid (ice)
– Liquid (water)
– Gas (water vapour or steam).
Change of state: Water can change from one form to another with temperature changes:
– Ice → Water = Melting
– Water → Vapour = Evaporation/Boiling
– Vapour → Water = Condensation
– Water → Ice = Freezing
The water cycle is the continuous movement of water in nature through evaporation, condensation, and precipitation.
Evaporation is faster when temperature, surface area, or wind speed increases.
Condensation forms dew, fog, and clouds.
Water plays a vital role in weather, climate, and maintaining life on Earth.
Human activities like pollution, wastage, and deforestation disturb the natural water cycle.
Conservation of water is essential—methods include rainwater harvesting, reducing wastage, and reusing water.
👉 👉Water constantly changes its form but remains the same precious resource. We must value, save, and use it wisely for a sustainable future.