
Water is an essential component for any living being to survive on Earth. Around 70% of our Earth is covered by water. So, being the only planet with water, the Earth is also called the ‘Blue Planet’. Water is present everywhere on Earth in different forms.
In this article, students will learn about the states of water, changes of state, and various physical properties of water.
After reading the concept, students will be able to:
The biosphere on Earth shows the presence of water in all three states, i.e. solid, liquid and gas.

Water can change from one state to another when its temperature increases or decreases. These changes in the state of water occur through processes such as freezing, melting, evaporation, and condensation.
Water has several unique properties that make it essential for life on Earth. These properties help us understand how water behaves in different situations and why it is useful for living organisms and everyday activities.
We see a river or pond where the colour water is greenish or brownish. The water in the ocean and seas looks bluish. Such colour appears due to aquatic plants, soil debris, different impurities, minerals, etc.

But the water in its pure form does not have any colour as it does not have any impurities.
Pure water is tasteless. The water we use in the house may contain some added minerals that give it a mild taste. The purest water is called distilled water.
Pure water is odourless. Drainage water looks black and gives off a foul smell because it is mixed with sewage. Water in juices or any cold beverage gets the colour/taste/smell of other food ingredients present in it.
Though water exists in all three forms, most water on Earth is in the liquid form.

Water in a liquid state can flow from one place to another. Fluidity is the ability of a substance to flow. Due to its fluidity, it is easily transported to various areas within the cities via pipes.
Ice acts as an excellent heat insulator. The Eskimos use this property to build their houses, called igloos.

Igloos are made with blocks of ice. These keep the inside of the house warmer than the cold surroundings.
Water, when it evaporates from a surface, absorbs the heat of that surface and cools it down to produce a cooling effect.
This is the reason why people sprinkle water on hot terraces in summer.
Also, our body cools down after we sweat in summer due to the cooling effect of water caused by evaporation.
A solvent is mainly a liquid in which other materials dissolve.
Water is used as a solvent on a large scale due to its excellent capacity for dissolving many solutes. So, water is called the ‘universal solvent’.

The combination of solute and solvent is called a solution. The solute is generally present in small quantities, whereas the solvent is in larger quantities.
So far, we have seen that water is one of the most important substances on Earth and is essential for the survival of all living organisms. It exists in three different states: solid, liquid, and gas and changes from one state to another through processes such as freezing, melting, evaporation, and condensation. Water also has several unique properties, including being colourless, tasteless, odourless, fluid in nature, a good heat insulator in the form of ice, and an excellent solvent.
The main properties of water are that it is colourless, tasteless, and odourless in its pure form. Water also has fluidity, acts as a solvent, shows a cooling effect during evaporation, and can exist in solid, liquid, and gaseous states.
Water is called a universal solvent because it can dissolve many substances, such as salt and sugar. However, it cannot dissolve all substances, including oils and fats.
Water exists in three states:
Solid (ice)
Liquid (water)
Gas (water vapour)
When water evaporates, it absorbs heat from the surface on which it is present. As a result, the surface becomes cooler. This is why sweating helps cool our body during hot weather.
Fluidity is the ability of a substance to flow. Water has fluidity in its liquid state, which allows it to move from one place to another and flow through rivers, pipes, and streams.
The freezing point of water is 0°C, where liquid water changes into ice. The boiling point of water is 100°C, where liquid water changes into water vapour.
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