The coordinate bond is absent in

Options

A. `NaNO_(3)`
B. `CaCO_(3)`
C. `O_(3)`
D. KNC

Answer

To determine which compound does not contain a coordinate bond, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Understanding Coordinate Bonds**:
- A coordinate bond (or dative bond) is formed when one atom donates both electrons to form a covalent bond. This typically occurs in compounds where one atom has a lone pair of electrons that can be shared.

2. **Analyzing NaNO3 (Sodium Nitrate)**:
- Sodium nitrate consists of Na⁺ and NO₃⁻ ions. The nitrate ion (NO₃⁻) has a resonance structure where one of the oxygen atoms forms a coordinate bond with nitrogen. Therefore, NaNO3 contains a coordinate bond.

3. **Analyzing CaCO3 (Calcium Carbonate)**:
- Calcium carbonate consists of Ca²⁺ and CO₃²⁻ ions. The carbonate ion (CO₃²⁻) is formed by covalent bonds between carbon and oxygen atoms. There are no coordinate bonds present in the carbonate ion. Thus, CaCO3 does not have a coordinate bond.

4. **Analyzing O3 (Ozone)**:
- Ozone is a molecule made up of three oxygen atoms. In its structure, one of the oxygen atoms forms a coordinate bond with another oxygen atom. Therefore, O3 contains a coordinate bond.

5. **Analyzing KCN (Potassium Cyanide)**:
- In potassium cyanide, the cyanide ion (CN⁻) contains a carbon atom triple-bonded to a nitrogen atom. The nitrogen can also form a coordinate bond with carbon, making KCN contain a coordinate bond.

6. **Conclusion**:
- After analyzing all the compounds, we find that the only compound that does not have a coordinate bond is **CaCO3 (Calcium Carbonate)**.

### Final Answer:
The coordinate bond is absent in **CaCO3 (Calcium Carbonate)**.

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