Concept:Collision theory states the necessary conditions for a reaction, but not every condition is physically required.
Explanation:The theory requires molecules to collide with enough kinetic energy to overcome the activation energy barrier.
The collision must also have the correct orientation so that the product can form.
Molecules must possess sufficient speed to overcome intermolecular forces of attraction.
However, the theory does not require that the collision be perfectly elastic, meaning no loss of energy.
In fact, collisions are generally inelastic because some energy is transferred during the collision.
Therefore, the condition that is not required is the first option.
Answer:A. come into contact without loss of energy on colliding with each other.