Which of the following statements is not true about angle of contact ?

Options

A. The value of contact for pure water and glass is zero
B. Angle of contact increases with increase in temperature of liquid
C. If the angle of contact of a liquid and a solid surface is less than `90^(0)` , then the liquid spreads on the surface of solid
D. Angle of contact doesnot depend upon the inclination of the solid surface to the liquid surface.

Explanation

To determine which statement is not true about the angle of contact, we will analyze each of the four statements provided.

### Step-by-Step Solution:

1. **Understanding Angle of Contact**:
The angle of contact (or contact angle) is defined as the angle formed between the tangent to the liquid surface and the tangent to the solid surface at the point of contact. It is influenced by the properties of the liquid and solid involved.

2. **Statement Analysis**:
- **Statement 1**: "The value of contact for pure water and glass is zero."
- This statement is true. For pure water on a clean glass surface, the angle of contact is indeed approximately 0 degrees, indicating perfect wetting.

- **Statement 2**: "The angle of contact increases with increase in temperature of liquid."
- This statement is also true. As temperature increases, the surface tension of the liquid decreases, which can lead to an increase in the angle of contact.

- **Statement 3**: "If the angle of contact of a liquid solid surface is less than 90 degrees, then the liquid spreads on the surface of the solid."
- This statement is true. A contact angle less than 90 degrees indicates that the liquid wets the surface, causing it to spread.

- **Statement 4**: "The angle of contact does not depend upon the inclination of the solid surface to the liquid surface."
- This statement is not true. The angle of contact is indeed influenced by the inclination of the solid surface. As the angle of inclination changes, the contact angle can also change.

3. **Conclusion**:
Based on the analysis, the statement that is not true about the angle of contact is **Statement 4**.

### Final Answer:
The statement that is not true about the angle of contact is: "The angle of contact does not depend upon the inclination of the solid surface to the liquid surface."

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