Insect moves over surface of water because of a

Options

A. Elasticity
B. Surface tension
C. Friction
D. Viscosity

Answer

### Step-by-Step Solution:

1. **Understanding Surface Tension**:
- Insects can move on the surface of water due to a phenomenon known as surface tension. Surface tension is the property of a liquid's surface that allows it to behave like a stretched elastic membrane.

2. **Molecular Forces at the Surface**:
- Water molecules at the surface experience different forces compared to those submerged. The molecules at the surface are pulled inward by the molecules beneath them, creating a net upward force. This results in a tension that keeps the surface intact.

3. **Behavior of Water**:
- Water tends to minimize its surface area due to surface tension. This is why water droplets form spherical shapes, as a sphere has the smallest surface area for a given volume.

4. **Insects on Water**:
- When an insect lands on the surface of the water, the surface tension provides enough upward force to support the weight of the insect, preventing it from sinking. This allows the insect to walk or move across the surface.

5. **Comparison with Human Weight**:
- Unlike insects, humans are much heavier and exert more force on the water surface. This force exceeds the surface tension, causing humans to sink when they try to stand on water.

6. **Conclusion**:
- Therefore, insects can move over the surface of water because of surface tension, which acts like an elastic membrane, supporting their weight.