Which is/are correct about protective colloids?

Options

A. Haemoglobin cannot be used as a protective
colloids
B. Protective colloids are responsible for the
stability of paints ink etc
C. Lyophobic colloids act as protective colloids
D. Gelatin is a better protective colloid than gum
arabic

Answer

To determine which statements about protective colloids are correct, we will analyze each option based on our understanding of protective colloids and their properties.

### Step-by-Step Solution:

1. **Understanding Protective Colloids**:
- Protective colloids are typically lyophilic colloids that are added in small quantities to lyophobic colloids.
- Their main function is to stabilize lyophobic colloids and prevent them from precipitating when electrolytes are added.

2. **Analyzing Option A**:
- **Statement**: Hemoglobin cannot be used as a protective colloid.
- **Analysis**: Hemoglobin is a lyophilic colloid. Since protective colloids are lyophilic, this statement is incorrect.
- **Conclusion**: Option A is **incorrect**.

3. **Analyzing Option B**:
- **Statement**: Protective colloids are responsible for the stability of paints, inks, etc.
- **Analysis**: This statement is true because protective colloids help maintain the stability of these products by preventing the precipitation of the dispersed phase.
- **Conclusion**: Option B is **correct**.

4. **Analyzing Option C**:
- **Statement**: Lyophobic colloids act as protective colloids.
- **Analysis**: This statement is incorrect. Lyophobic colloids are not used as protective colloids; rather, lyophilic colloids serve this purpose.
- **Conclusion**: Option C is **incorrect**.

5. **Analyzing Option D**:
- **Statement**: Gelatin is a better protective colloid than gum arabic.
- **Analysis**: To compare their effectiveness, we can refer to the gold number. Gelatin has a lower gold number (0.005 to 0.01) compared to gum arabic (0.15 to 0.25), indicating that gelatin is indeed a better protective colloid.
- **Conclusion**: Option D is **correct**.

### Final Answer:
The correct statements about protective colloids are:
- **B**: Protective colloids are responsible for the stability of paints, inks, etc.
- **D**: Gelatin is a better protective colloid than gum arabic.