PHYSICS [2 Mark Question Answer]

The particles of matter called molecules have the following characteristics:

1. They are very small in size.
2. They have spaces between them.
3. They are in constant random motion.
4. They always attract each other.

Atoms :
1. it is the smallest part of an element.
2. It does not have an independent existence
Molecules :
1. It is the smallest part of a compound.
2. It has an independent existence.

Add one teaspoon of sugar to it and stir. The sugar disappears but the level of water in the glass does not rise that means the volume of water has not increased. Because the sugar particles are adjusted between the water molecules. This shows that there are intermolecular gaps in water.

Scent fumes (molecules) being gases fill the spaces between air molecules and the molecules of air fill the spaces between scent molecules due to diffusion, fumes spread into a room.
OR
Due to the inter-mixing of scent molecules and air molecules, scent fumes spread into the room.

You will see that some water flows out of the tumbler and collects in the bowl. Remove the stone from the tumble. The level of water in the tumbler comes down. Now, pour the water collected in the bowl back into the tumbler. The glass tumbler is filled again. This is because the stone occupied space and therefore drives the water out of the tumbler. This proves that not only solids but liquids also occupy space.

The force of attraction between the molecules of a given substance is called intermolecular force and the space between these molecules is called intermolecular space.
The basic relation between the two is that they are inversely proportional to each other. More is the intermolecular force lesser is the intermolecular space and vice-versa.

Water from oceans, rivers lakes from leaves of trees (transperation) changes into vapours when the temperature increases or evaporates and enters the atmosphere as clouds when the temperature falls the vapours change into the water and some of it in the form of snowfall on mountains and earth in the form of water and hales and this continues. Thus water cycle is an example of interconversion of states of water.