When a river enter the sea a delta is formed formation of delta is due to

Options

A. Peptization
B. Coagulation
C. Emulsification
D. Dialysis

Explanation

### Step-by-Step Solution:

1. **Understanding the Composition of River Water**:
- River water contains various substances, including electrolytes, clay particles, and sand. These components are often present in a colloidal form, meaning they are suspended in the water but not dissolved.

2. **Interaction with Sea Water**:
- When the river water enters the sea, it encounters seawater, which is rich in salts (electrolytes). The presence of these salts is crucial for the next step.

3. **Coagulation Process**:
- The salts in the seawater cause the clay and sand particles that were suspended in the river water to coagulate. Coagulation is a process where particles clump together, often due to the neutralization of their charges.

4. **Formation of Delta**:
- As the clay and sand particles coagulate, they become heavier and begin to sink to the bottom. This accumulation of sediments at the mouth of the river leads to the formation of a delta.

5. **Conclusion**:
- The formation of a delta is primarily due to the coagulation of colloidal particles (clay and sand) when river water meets seawater, resulting in sediment deposition.

### Final Answer:
The formation of a delta when a river enters the sea is due to the coagulation of colloidal particles in the river water, which occurs because of the interaction with the salts present in seawater.

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