Question

Give reason: We can easily move our hand in air but to do the same through a solid block of wood or brick, we need a karate expert.

Answer 1

1. Intermolecular space is the space between two molecules or atoms.
2. In solid, the intermolecular space is the least, whereas in gas, the intermolecular space is the most.
3. As a result, the intermolecular force is the most in solids and the least in gases.
4. The wooden block is a solid & hence its molecules are tightly packed whereas in air which is a gas its molecules are loosely packed.
5. Hence, air molecules have very less intermolecular force between them and a very small external force can separate them and pass through it. So, we can easily move our hand in air. Wooden or brick block has strong intermolecular force. Thus in order to move hand through the solid, we need a karate expert who can break that strong intermolecular force.