1. Put your finger inside the solid wooden block.
2. Put ink on the wooden block, it will remain on the top.

You cannot. As there is no inter molecular space between the molecules of solid objects.

3. Now try to put your finger inside the water in the glass. This shows that water has some inter molecular space.
4. Move your hand in air. You can easily move your hand as there is maximum space between the molecules.
5. Take a glass of water and add one drop of colour into it.
6. Leave it for some time.

You will observe that the colour is randomly moving in water and mixing in it. It will thoroughly be mixed with water because the colour molecules enter into the space between the molecules of water.

7. Again, take one glass of water, and add one spoon of salt into it. Stir it well.

You will observe that the salt is completely dissolved in water. The molecules of salt enter into the space between the molecules of water.