Final answer:
Coagulants are used to neutralize the electrical charge of colloidal particles, causing them to flocculate and settle, which assists in the water treatment process. The correct option is B.
Step-by-step explanation:
The substance that can be used to neutralize the electrical charge of colloidal particles and enable them to flocculate, increasing in size so that they will settle out, is B) Coagulants.
Coagulation and flocculation are key processes in water treatment where chemicals with a positive charge are added to the water. These positively charged chemicals neutralize the negatively charged dirt and other dissolved particles in the water.
Substances like alum and lime are examples of coagulants that are used to adjust the pH and facilitate the formation of larger particles, known as floc, which can then be more easily removed from the water.
When we talk about coagulation, we refer to the small, charged colloidal particles in the water binding together with the coagulants to form larger particles. The charged nature of these colloidal particles helps in keeping them suspended.
However, when coagulants like alum are added, the process of neutralizing the charges allows for precipitation and settling. This is a critical step in the purification and treatment of water, making it suitable for various uses. The correct option is B.