total number of Boron atoms in anionic part of borax which participate in back bonding.

Explanation

To determine the total number of boron atoms in the anionic part of borax that participate in back bonding, we can follow these steps:

### Step 1: Write the formula for borax
The chemical formula for borax is \( \text{Na}_2\text{B}_4\text{O}_5(\text{OH})_4 \cdot 8 \text{H}_2\text{O} \). In this formula, we can identify that there are 4 boron atoms in the anionic part, which is \( \text{B}_4\text{O}_5(\text{OH})_4 \).

**Hint:** Look for the chemical formula of borax to identify the number of boron atoms present.

### Step 2: Analyze the structure of the anionic part
The anionic part consists of boron and oxygen atoms. When we draw the structure, we can see that the boron atoms are connected to oxygen atoms and hydroxyl (OH) groups. Each boron atom in the structure can be classified based on its hybridization.

**Hint:** Visualize the structure to understand how boron and oxygen atoms are arranged.

### Step 3: Determine the hybridization of boron atoms
In the structure of borax:
- Some boron atoms are sp² hybridized, which means they have three bond pairs and no lone pairs.
- Others may be sp³ hybridized, which means they have four bond pairs.

**Hint:** Recall the criteria for hybridization to classify each boron atom.

### Step 4: Identify which boron atoms participate in back bonding
Only the sp² hybridized boron atoms participate in π-π back bonding. In the case of borax, we find that there are 2 boron atoms that are sp² hybridized.

**Hint:** Focus on the hybridization type that allows for back bonding.

### Step 5: Conclude the total number of boron atoms involved in back bonding
Since we have identified that only 2 boron atoms are sp² hybridized, we conclude that the total number of boron atoms in the anionic part of borax that participate in back bonding is 2.

**Final Answer:** The total number of boron atoms in the anionic part of borax that participate in back bonding is **2**.

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