Species having maximum 'Cl-O' bond order is :

Options

A. `ClO_(3)^(-)`
B. `ClO_(3)`
C. `ClO_(2)`
D. `ClO_(2)^(-)`

Explanation

To determine the species with the maximum 'Cl-O' bond order among the given options (ClO3^-, ClO3, ClO2, ClO2^-), we will analyze the bond orders of each species step by step.

### Step 1: Analyze ClO3^-
1. **Valence Electrons**: Chlorine (Cl) has 7 valence electrons. In ClO3^-, there is one extra electron due to the negative charge, giving a total of 8 valence electrons.
2. **Bond Formation**:
- Each of the three oxygen atoms forms bonds with chlorine.
- Two of the oxygen atoms form double bonds with chlorine, and one oxygen forms a single bond.
3. **Lone Pairs**: After forming these bonds, chlorine has one lone pair remaining.
4. **Bond Order Calculation**:
- Total bonds = 2 (double bonds) + 1 (single bond) = 5 bonds.
- Bond order = Total bonds / Number of bond pairs = 5/3 = 1.67 (approximately).

### Step 2: Analyze ClO3
1. **Valence Electrons**: Chlorine has 7 valence electrons, and in ClO3, all are used to bond with oxygen.
2. **Bond Formation**:
- Each of the three oxygen atoms forms a double bond with chlorine.
3. **Lone Pairs**: There are no lone pairs on chlorine in this case.
4. **Bond Order Calculation**:
- Total bonds = 3 (double bonds).
- Bond order = Total bonds / Number of bond pairs = 3/3 = 1.

### Step 3: Analyze ClO2
1. **Valence Electrons**: Chlorine has 7 valence electrons.
2. **Bond Formation**:
- One oxygen forms a double bond with chlorine, and the other oxygen forms a coordinate bond.
3. **Lone Pairs**: There is one lone pair on chlorine.
4. **Bond Order Calculation**:
- Total bonds = 2 (one double bond and one coordinate bond).
- Bond order = Total bonds / Number of bond pairs = 2/2 = 1.

### Step 4: Analyze ClO2^-
1. **Valence Electrons**: Chlorine has 7 valence electrons, and there is one extra electron due to the negative charge, giving a total of 8 valence electrons.
2. **Bond Formation**:
- One oxygen forms a double bond, and the other oxygen forms a single bond with chlorine.
3. **Lone Pairs**: There are two lone pairs on chlorine.
4. **Bond Order Calculation**:
- Total bonds = 3 (one double bond and one single bond).
- Bond order = Total bonds / Number of bond pairs = 3/2 = 1.5.

### Conclusion
After analyzing all the species:
- ClO3^- has a bond order of approximately 1.67.
- ClO3 has a bond order of 1.
- ClO2 has a bond order of 1.
- ClO2^- has a bond order of 1.5.

Thus, the species with the maximum 'Cl-O' bond order is **ClO3^-**.

### Final Answer
The species having maximum 'Cl-O' bond order is **ClO3^-**.