Sphere of influence .

Explanation

### Step-by-Step Solution for Sphere of Influence

1. **Definition of Sphere of Influence**:
The sphere of influence refers to the spherical space or volume around a molecule within a substance. Within this sphere, the central molecule can exert attractive forces on other surrounding molecules.

2. **Visualizing the Sphere**:
Imagine a container filled with a liquid, such as water. Consider a specific molecule located at a certain point within this liquid.

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