Page 235 - New Medley 4 Semester 2 PDF (Merged)

This process is called melting. When water is boiled till 100°C, it changes into water

vapour. This process is called evaporation. When water vapour changes back to
water on cooling, it is called condensation.

Meltingofice Vaporisation of water
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Freezingofwater Condensationofwater vapour

Ice Water Water vapour
(solid state) (liquid state) (gaseous state)
1 • Remembering

Write Yes or No.
1. Liquids take the shape of their container easily.

2. Solids have a fixed shape but their volume is not fixed.
3. There are three states of matter.

4. Water changes into ice at 0°C.

SOLUTION
• Analysing/Hands-on Learning
Activity

Half fill a glass tumbler with water and add two teaspoonfuls
of sugar in it. Stir the sugar in the water.
Can you see the sugar after stirring?

Where has the sugar gone?

Sugar dissolves in water after stirring. When a solid dissolves in a liquid, it forms

a solution. In this case, sugar is a solute and water is a solvent.

Solute + Solvent  Solution

Solids dissolve in liquids

When a solid dissolves in a liquid to form a solution, the solution is called solid
in liquid solution.

Solids which dissolve in water are called soluble solids. Sugar, salt, alum, etc.

are soluble solids.
Solids which do not dissolve in water are called insoluble solids. Sand, saw

dust, straw, etc., are insoluble solids.

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