The particles must be in the correct orientation upon impact.
The particles must collide with enough energy to meet the activation energy of the reaction.
Explanation:
This a problem related to chemical kinetics. The collision theory is one of the theories of reaction rates and it perfectly explains how the effectiveness of colliding molecules dictates the pace of a reaction.
For reactions to occur, there must be collisions between reacting particles. It implies that the collision per unit time and how successful collisions are determines the rate of chemical reactions in most cases. Therefore, for a collision to be successful, colliding particle must have enough energy which is greater than the activation energy of the reaction. In order to also produce the desired products, the colliding particles must be properly oriented.
If Star A appears to move back and forth by a greater amount than Star B, which star do you think is actually closer to you? Star A. If the parallax angle for a star is 1 arcsecond, what is the distance from the Sun to that star