Total number of `OH` present on all boron atoms in colemanite `Ca_(2)B_(6)O_(11).5H_(2)O` is

Explanation

To determine the total number of `OH` groups present on all boron atoms in colemanite, which has the chemical formula `Ca_(2)B_(6)O_(11).5H_(2)O`, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Composition of Colemanite**:
- The formula for colemanite is `Ca_(2)B_(6)O_(11).5H_(2)O`.
- This indicates that there are 6 boron (B) atoms in the structure.

2. **Understanding the Structure**:
- Colemanite has a complex structure where boron atoms are typically bonded to hydroxyl (`OH`) groups and oxygen atoms.
- Each boron atom can be coordinated with hydroxyl groups.

3. **Count the Hydroxyl Groups**:
- In the structure of colemanite, it is known that each boron atom is typically associated with one hydroxyl group.
- Therefore, if there are 6 boron atoms, we can assume that there are 6 hydroxyl groups.

4. **Final Calculation**:
- Since each of the 6 boron atoms is bonded to one `OH` group, the total number of `OH` groups is simply the number of boron atoms.
- Total `OH` groups = 6 (from 6 boron atoms).

### Conclusion:
The total number of `OH` groups present on all boron atoms in colemanite is **6**.

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