Which of the following does not exist ?

Options

A. `ClO_(4)^(-)`
B. `CO_(3)^(2-)`
C. `SO_(4)^(2-)`
D. `ZnBr`

Explanation

To determine which of the following compounds does not exist, we will analyze each option provided:

1. **ClO4- (Perchlorate Ion)**:
- The perchlorate ion is a well-known polyatomic ion consisting of one chlorine atom and four oxygen atoms. It carries a negative charge.
- **Conclusion**: ClO4- exists.

2. **CO3 2- (Carbonate Ion)**:
- The carbonate ion is another common polyatomic ion made up of one carbon atom and three oxygen atoms, with a charge of -2.
- **Conclusion**: CO3 2- exists.

3. **SO4 2- (Sulfate Ion)**:
- The sulfate ion consists of one sulfur atom and four oxygen atoms, and it carries a -2 charge. This ion is also widely recognized in chemistry.
- **Conclusion**: SO4 2- exists.

4. **ZnBr (Zinc Bromide)**:
- Here, we need to clarify that ZnBr as written does not exist as a stable compound. Zinc typically forms a +2 oxidation state and combines with bromine to form ZnBr2 (zinc bromide), which is the correct formula for the compound.
- **Conclusion**: ZnBr does not exist as a stable compound.

### Final Answer:
The compound that does not exist is **ZnBr** (Option D).

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