Finely powered or colloidal catalyst particles having……………..surface…………………..are rich in ………………………… valencies.

Answer

To solve the question, we need to fill in the blanks based on our understanding of catalysts, surface area, and valencies in the context of surface chemistry.

1. **Understanding the Question**: The question is asking about the characteristics of finely powdered or colloidal catalyst particles in terms of their surface area and valencies.

2. **Identifying the Key Concepts**:
- **Finely powdered or colloidal catalysts**: These forms of catalysts have a high surface area which allows for more active sites for reactions.
- **Surface area**: The larger the surface area, the more opportunities there are for reactants to interact with the catalyst.
- **Valencies**: Refers to the number of bonds that an atom can form. In the context of catalysts, free valencies are important because they indicate the availability of active sites for adsorption.

3. **Filling in the Blanks**:
- The first blank can be filled with "large" to indicate that finely powdered or colloidal catalyst particles have a large surface area.
- The second blank can be filled with "area" to specify that we are indeed talking about surface area.
- The third blank can be filled with "free" to indicate that these catalysts are rich in free valencies, meaning they have many available sites for adsorption.

4. **Final Answer**:
- "Finely powered or colloidal catalyst particles having **large** surface **area** are rich in **free** valencies."