Which of the following is not correct  

Options

A. Milk is naturally occuring emulsion
B. Gold sol is a lyophilic sol
C. Physical adsorption decreases with rise in temperature
D. Chemical adsorption is unilayered.

Answer

To solve the question "Which of the following is not correct?", we will analyze each option provided.

### Step-by-Step Solution:

1. **Analyze Option 1: Milk is a naturally occurring emulsion.**
- An emulsion is a colloidal solution where liquid droplets are dispersed in another liquid. Milk consists of fat globules dispersed in water, making it a liquid-in-liquid colloidal solution. Since milk is indeed a naturally occurring emulsion, this statement is **correct**.

2. **Analyze Option 2: Gold salt is a lyophilic salt.**
- Lyophilic colloids are stable and can easily be dispersed in a solvent. However, gold salts are classified as lyophobic colloids, which means they are not stable and tend to precipitate easily. Therefore, this statement is **incorrect**.

3. **Analyze Option 3: Physical adsorption decreases with rising temperature.**
- Physical adsorption is a process that is generally reversible and involves weak van der Waals forces. As temperature increases, the kinetic energy of the molecules increases, which can lead to desorption. Thus, physical adsorption does indeed decrease with rising temperature, making this statement **correct**.

4. **Analyze Option 4: Chemical adsorption is unilayered.**
- Chemical adsorption involves the formation of strong chemical bonds between the adsorbate and the adsorbent. Once these bonds are formed, there is no room for additional layers to form due to the strong nature of the bonds. Therefore, chemical adsorption is indeed unilayered, making this statement **correct**.

### Conclusion:
The statement that is not correct is **Option 2: Gold salt is a lyophilic salt**.

### Final Answer:
**Option 2 is the incorrect statement.**

---