What describes the effect of an effective collision on reaction rate?

• A. It decreases the rate
• B. It has no effect on rate
• C. It consumes reactants without product formation
• D. It increases the rate as particles line up in such a way that a reaction occurs upon collision

Answer: (D)

In chemical kinetics, only collisions that have enough energy and the right orientation are productive. When a collision is productive, reactants rearrange to form products, which increases the rate because more product-forming events occur per unit time. The description that particles line up in such a way that a reaction occurs upon collision captures this idea: proper alignment means the bonds can break and form new ones in a single encounter, making that collision contribute to the rate. The other statements don’t fit because decreasing the rate, having no effect, or collisions that consume reactants without producing products would not reflect the increase in reaction rate that comes from productive, energy- and orientation-enabled collisions.