Page 113 - ACTIVE SCIENCE 4 TOC

LET’S
REVISE

• There are different things around us like air, water, trees, etc. All these things have
mass and occupy space, which is called matter.

• The particles of solids do not have space, so they cannot move around.
• Liquids have a fixed volume but do not have fixed shape. Particles of liquids are not

close to each other, so, they cannot move around.
• The particles of gases can easily move in any direction. They do not have fixed shape
and fixed volume.

• We can change the state of matter from liquid to solid and solid to gas.

Glossary
• Melting : Process in which, on heating, a solid changes into liquid.

• Freezing : Process in which a liquid changes into a solid.
• Evaporation : Process in which, on heating, liquid changes into gas.

• Condensation : When gas changes its state into liquid with contact of cold
surface.

• Solute : The solid that is dissolved in the liquid.
• Solvent : The liquid in which the solute is dissolved.
• Solution : Liquid obtained after dissolving a solute into a solvent.

Practice Time

A. Tick the correct option.
1. Liquids do not have fixed _____________.

a. shape b. volume
c. space d. value

2. Gas particles can move in _____________.

a. any direction b. one direction
c. both directions d. none of these

3. Gases do not have fixed _____________.
a. volume b. space

c. value d. none of these

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