Most colloidal particles in water are negatively charged:
- Colloidal particles are particles that are intermediate in size between individual atoms or molecules and bulk solids. They range in size from 1 to 1000 nanometers. Examples of colloidal particles include proteins, nanoparticles, and clay particles.
- When colloidal particles are dispersed in water, they tend to acquire an electrical charge. This charge arises from the dissociation of surface groups on the particles or the adsorption of ions from the surrounding medium.
- In most cases, colloidal particles in water are negatively charged. This is because many natural substances, such as clays and organic matter, have negatively charged surface groups. These surface groups can dissociate in water, releasing negatively charged ions into the solution.
- The negative charge on colloidal particles helps to stabilize the colloidal dispersion. The particles repel each other due to their like charges, preventing them from aggregating or settling out of the solution. This electrostatic repulsion is known as the electrostatic stabilization mechanism.

The surface charge on colloidal particles is the major contributor to their long-term stability:
- The stability of a colloidal dispersion refers to its ability to remain dispersed and resist aggregation or settling over time.
- The surface charge on colloidal particles plays a crucial role in determining the stability of the dispersion. It is the major contributor to the long-term stability of colloidal systems.
- The electrostatic repulsion between like-charged particles prevents them from coming into close contact and forming aggregates. This repulsion is responsible for the stability of the dispersion.
- The strength of the electrostatic repulsion is influenced by factors such as the magnitude of the surface charge, the distance between particles, and the presence of electrolytes in the solution.
- Other factors such as steric hindrance (caused by adsorbed or grafted polymer chains on the particle surface) and van der Waals forces (attractions between particles) also contribute to the stability of colloidal dispersions, but the surface charge is generally the dominant factor.

In conclusion, both statements are correct. Most colloidal particles in water are negatively charged, and the surface charge on colloidal particles is the major contributor to their long-term stability.