A reaction occurs when solid X is placed into solution Y. As a result, the temperature of the new solution increases by 3°C. The temperature rises another 2°C when more of solid X is added to the solution. What does this indicate about the effect of adding more solid?

A. It increased the number of molecular collisions.
B. It decreased the number of molecular collisions.
C. It decreased the space between the molecules and lowered the reaction rate.
D. It increased the space between the molecules and increased the reaction rate.

It increased the number of molecular collisions is the indication about the effect of adding more solid.

Option: A

Explanation:

The collision theory states that a reaction occurs when there is collision between the particles. i.e (atoms, ions, or molecules). When a solid is added, there is increase in temperature of the solution.This is because of the result of the reaction of solid X when it is placed into the solution. The main postulate of the collision theory is that the particles have to collide to react.

So, the amount of particles is an important factor for the reaction rate. The rise in temperature when the solid is added to the solution is evident from this postulate as when there are more particles, there would be more collisions.As a result, there would be more reactions which results in increase in temperature.