What is the value of X in the given chemical formula of crystalline
borax ?
`Na_2[B_4O_5 (OH)_4] X H_2O`

Explanation

To determine the value of X in the given chemical formula of crystalline borax, we can follow these steps:

### Step 1: Understand the Chemical Formula
The given formula is:
\[ \text{Na}_2[\text{B}_4\text{O}_5(\text{OH})_4] \cdot X \text{H}_2\text{O} \]

### Step 2: Identify the Known Formula of Borax
The common formula for borax is:
\[ \text{Na}_2\text{B}_4\text{O}_7 \cdot 10 \text{H}_2\text{O} \]
This indicates that borax typically contains 10 water molecules of crystallization.

### Step 3: Compare with the Given Formula
In the provided formula, we see that it is represented differently:
\[ \text{Na}_2[\text{B}_4\text{O}_5(\text{OH})_4] \cdot X \text{H}_2\text{O} \]
Here, the boron-oxygen structure is slightly different, which indicates a different hydration state.

### Step 4: Determine the Value of X
From the information provided in the video transcript, it is stated that in this representation, the value of X is 8. This means that the crystalline borax in this particular formula contains 8 water molecules of crystallization.

### Conclusion
Thus, the value of X in the formula of crystalline borax is:
\[ X = 8 \]

---