Which of the following is/are correct statement(s)?

Options

A. Hardy Schulze rule is related to coagulation.
B. Tyndall effect is shown by mainly colloids
C. When liquid is dispersed in liquid, it is called gel
D. gold number is a measure of protective power of lyophilic colloid.

Answer

To solve the question of which statements are correct regarding colloids and their properties, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement 1: The Hardy-Shelzhul law is related to coagulation.**
- The Hardy-Shelzhul law states that the greater the valency of the coagulating ion, the greater its power to bring about coagulation. This statement is correct.

2. **Statement 2: The Tyndall effect is shown by mainly colloids.**
- The Tyndall effect refers to the scattering of light by colloidal particles. This phenomenon is primarily observed in colloidal solutions. Therefore, this statement is also correct.

3. **Statement 3: When liquid is dispersed in liquid, it is called gel.**
- This statement is incorrect. When a liquid is dispersed in another liquid, it forms an emulsion, not a gel. A gel is formed when a liquid is dispersed in a solid.

4. **Statement 4: The gold number is a measure of the protective power of the lyophilic colloid.**
- The gold number is indeed a measure of the protective action of lyophilic colloids. This statement is correct.

### Conclusion:
- The correct statements are:
- Statement 1: Correct
- Statement 2: Correct
- Statement 3: Incorrect
- Statement 4: Correct

Thus, the correct statements are 1, 2, and 4.