The process of coagulation involves which of the following reactions?

Coagulation is a critical process in water treatment that involves multiple stages and types of reactions. Selecting the correct answer highlights an understanding of these different stages.

In the coagulation process, particulates in water are destabilized, typically by the addition of coagulants, which often leads to a chemical reaction. This reaction modifies the surface charges of the particles, allowing them to aggregate or agglomerate into larger clusters. This agglomeration is a physical manifestation that results from the previous chemical changes.

The combination of chemical reactions, physical reactions, and agglomeration accurately reflects the entirety of the coagulation process, as it starts with the coagulants interacting chemically with the particles to encourage aggregation. The subsequent agglomeration of these particles leads to improved sedimentation during the next phase of water treatment.

By focusing on the comprehensive nature of coagulation, it's clear why a combination of all these factors is essential in the effectiveness of the process. The other options, while they may include elements related to coagulation, do not fully address its complexity. For instance, focusing solely on physical reactions ignores the necessity of the chemical interactions that initiate the coagulation process.