According to…………..theory of catalyiss, there are some……….centres with……….valencies.

Answer

**Step-by-Step Text Solution:**

1. **Identify the Theory of Catalysis:**
The question asks for a specific theory of catalysis. The relevant theory here is the **adsorption theory of catalysis**.

2. **Fill in the First Blank:**
According to the adsorption theory of catalysis, there are some **active centers**. These centers are crucial for the catalytic process as they facilitate the adsorption of reactants.

3. **Fill in the Second Blank:**
These active centers have **free valencies**. Free valencies refer to the available bonding sites on the active centers where reactant molecules can attach.

4. **Complete the Statement:**
Therefore, the complete statement is: "According to **adsorption theory** of catalysis, there are some **active centers** with **free valencies**."

**Final Answer:**
"According to adsorption theory of catalysis, there are some active centers with free valencies."

---