Surface tension decreases with increase in .......

Explanation

**Step-by-Step Solution:**

1. **Understanding Surface Tension**:
- Surface tension is a property of liquids that causes the surface to behave like a stretched elastic membrane. It is the tendency of liquid surfaces to shrink into the minimum surface area possible.

2. **Molecular Behavior at the Surface**:
- Molecules at the surface of a liquid experience an inward pull due to the attraction from the molecules beneath them. This creates a net inward force, which is what we refer to as surface tension.

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