Which of the following molecules does not have co-ordinate bond?

Options

A. `PH_(4)^(+)`
B. `NO_(2)`
C. `O_(3)`
D. `CO_(3)^(2-)`

Answer

To determine which of the given molecules does not have a coordinate bond, we will analyze each molecule step by step.

### Step 1: Understand Coordinate Bonds
A coordinate bond (or dative bond) is formed when one atom donates a pair of electrons to another atom that has an empty orbital. This is typically represented with an arrow pointing from the donor atom to the recipient atom.

### Step 2: Analyze Each Molecule

#### Molecule 1: PH₃ (Phosphine)
- **Structure**: Phosphorus (P) has one lone pair of electrons and forms three single bonds with hydrogen (H).
- **Coordinate Bond Formation**: When PH₃ donates its lone pair to form PH₄⁺, a coordinate bond is formed.
- **Conclusion**: PH₃ has a coordinate bond.

#### Molecule 2: NO₂ (Nitrogen Dioxide)
- **Structure**: Nitrogen (N) is bonded to two oxygen (O) atoms, one with a double bond and the other with a single bond. N has one unpaired electron.
- **Coordinate Bond Formation**: The unpaired electron can be shared with an oxygen atom, forming a coordinate bond.
- **Conclusion**: NO₂ has a coordinate bond.

#### Molecule 3: O₃ (Ozone)
- **Structure**: Ozone consists of three oxygen atoms, with a resonance structure involving double bonds and a lone pair.
- **Coordinate Bond Formation**: The resonance structure allows for the formation of coordinate bonds between the oxygen atoms.
- **Conclusion**: O₃ has a coordinate bond.

#### Molecule 4: CO₃²⁻ (Carbonate Ion)
- **Structure**: Carbon (C) is bonded to three oxygen atoms, with one double bond and two single bonds. The overall charge is -2.
- **Coordinate Bond Formation**: In the carbonate ion, all bonds are covalent (sigma and pi bonds) and there are no lone pairs on carbon that can donate electrons.
- **Conclusion**: CO₃²⁻ does not have a coordinate bond.

### Final Answer
The molecule that does not have a coordinate bond is **CO₃²⁻ (Carbonate Ion)**.

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