Molecule containing coordinate covalent bond among the following is :

Options

A. `H_(2)O`
B. `HNO_(3)`
C. `BaCI_(2)`
D. `CaO`

Explanation

To determine which molecule contains a coordinate covalent bond, we need to understand what a coordinate covalent bond is. A coordinate covalent bond, also known as a dative bond, is formed when one atom donates both of the electrons that are shared in the bond. This typically occurs between a Lewis acid (an electron pair acceptor) and a Lewis base (an electron pair donor).

### Step-by-Step Solution:

1. **Identify the Molecules**: Look at the list of molecules provided in the question. Common examples include NH3 (ammonia), H2O (water), CO2 (carbon dioxide), and BF3 (boron trifluoride).

2. **Determine Electron Pair Donors and Acceptors**:
- **NH3**: Ammonia has a lone pair of electrons on the nitrogen atom, which can be donated.
- **H2O**: Water also has lone pairs on the oxygen atom.
- **CO2**: Carbon dioxide does not have any lone pairs available for donation.
- **BF3**: Boron trifluoride is an electron-deficient molecule and can accept a pair of electrons.

3. **Identify the Coordinate Covalent Bond**:
- In the case of **NH3** and **BF3**, when ammonia donates its lone pair to boron trifluoride, a coordinate covalent bond is formed. This is represented as:
\[ \text{NH}_3 + \text{BF}_3 \rightarrow \text{NH}_3\text{BF}_3 \]
- The bond between nitrogen and boron in this complex is a coordinate covalent bond.

4. **Conclusion**: The molecule that contains a coordinate covalent bond among the options is **NH3BF3**.

### Final Answer:
The molecule containing a coordinate covalent bond among the following is **NH3BF3**.