What enables us to write on the black board with chalk

The correct option is Adhesion.

To understand why we can write on a blackboard with chalk, we need to look at the forces acting between different substances:
1. Adhesion (Adhesive force): This is the force of attraction between molecules of different types. In this case, it is the attractive force between the chalk molecules and the blackboard surface molecules.
2. Cohesion (Cohesive force): This is the force of attraction between molecules of the same type, such as between chalk molecules themselves.

When chalk is pressed and moved against a blackboard, the adhesive force between the chalk particles and the blackboard surface is stronger than the cohesive force holding the chalk particles together. As a result, chalk particles break away from the chalk stick and stick to the rough surface of the blackboard, allowing us to write. Therefore, adhesion is the force that enables this process.