How does an increase in reactant concentration affect the rate of reaction? it leads to more frequent collisions, which increase reaction rate. it leads to less frequent collisions, which increase reaction rate. it leads to more frequent collisions, which decrease reaction rate. it leads to less frequent collisions, which decrease reaction rate.

Option (a) is the correct answer.

Explanation:

According to collision theory, more is the number of molecules present in a chemical reaction more will be the number of collisions between them.

Therefore, when we increase the concentration of reactants then it means we are increasing the number of molecules.

Hence, we can conclude that out of the given options, an increase in reactant concentration will affect the rate of reaction because it leads to more frequent collisions, which increase reaction rate.