Page 95 - Science Class 6 Times Publication

6. Make holes in one of the balloons with a
hot needle. What happens?

Observation: The air comes out from the holes
of the balloon and its mass decreases whereas
mass of the another balloon remains constant.
So, the bar inclines towards that balloon which

is not broken.

Conclusion: The balloon having more mass is
heavier and it makes the rod incline downwards.

Atoms and molecules

All matters are composed of small particles. These small particles

are called molecules. The molecules are so small that they cannot
be seen with naked eyes. Thus, molecules are the smallest particles
of a substance which can exist freely and contain all properties of the
substances.

Molecules are attracted with each other by a force called intermolecular
force. There is a space between molecules called intermolecular space.
Inter-molecular
space Gas

Solid
Liquid molecules

Solid molecules Liquid molecules Gas molecules

The molecules of solids are tightly packed. The molecules of liquids
are loosely packed while the molecules of gas are apart from each
other.

Molecules can also be further sub-divided into atoms. But, atoms
cannot be further divided. Atoms combine together to form molecules.
Atoms take part in chemical reactions.

Thus, an atom is the smallest particle of a matter which can take part
in a chemical reaction.

Times' Crucial Science and Environment 91 Book 6