In collision theory, collisions are either effective or noneffective. Which option reflects that?

• A. Collisions are effective or noneffective
• B. Collisions always lead to products
• C. All collisions result in products
• D. Only collisions at high energy produce products

Answer: (A)

In collision theory, a collision either leads to a reaction or it doesn’t. An effective collision occurs when two reactant molecules collide with enough energy to overcome the activation barrier and with a favorable orientation so the chemical bonds can rearrange into products. If either the energy is too low or the molecules don’t hit in the right arrangement, the collision is ineffective and no reaction happens. This binary view—effective versus noneffective—best captures how collisions govern whether a reaction proceeds.

The other ideas oversimplify or misstate the situation. Not every collision produces products, since energy and orientation aren’t guaranteed to be right, and saying that all collisions or only high-energy collisions produce products ignores the roles of activation energy and molecular orientation. Higher energy increases the chance of a reaction but is not the sole determinant, and some collisions at lower energies can be effective if the geometry is favorable.