Which of the hydrated species may exist?
I : `H_(5)O_(2)^(+)` , II : `H_(3)O^(+)` , III : `H_(3)O_(2)^(-)` , IV : `H_(7)O_(3)^(+)`

Options

A. II only
B. I and II
C. I, II and IV
D. I, II, III and IV

Answer

To determine which of the given hydrated species may exist, we will analyze each species one by one based on their composition and the principles of hydration in aqueous solutions.

### Step 1: Analyze `H3O^(+)`
- **Explanation**: The species `H3O^(+)` is known as the hydronium ion. It is formed when water (H2O) accepts a proton (H+). This is a well-known hydrated species in aqueous solutions.
- **Conclusion**: `H3O^(+)` exists as a hydrated species.

### Step 2: Analyze `H3O2^(-)`
- **Explanation**: The species `H3O2^(-)` can be formed when water combines with hydroxide ions (OH^-) and can be considered a hydrated species. It represents a form of water that has accepted an additional proton, resulting in a negatively charged ion.
- **Conclusion**: `H3O2^(-)` exists as a hydrated species.

### Step 3: Analyze `H5O2^(+)`
- **Explanation**: The species `H5O2^(+)` can be formed by combining two water molecules with a proton (H+). This indicates that it has a structure that accommodates additional water molecules, making it a hydrated species.
- **Conclusion**: `H5O2^(+)` exists as a hydrated species.

### Step 4: Analyze `H7O3^(+)`
- **Explanation**: The species `H7O3^(+)` can be formed by further hydration of `H5O2^(+)` with additional water molecules. This indicates that it can also exist as a hydrated species in aqueous solutions.
- **Conclusion**: `H7O3^(+)` exists as a hydrated species.

### Final Conclusion
All four species:
1. `H3O^(+)`
2. `H3O2^(-)`
3. `H5O2^(+)`
4. `H7O3^(+)`

can exist as hydrated species.

### Summary of the Answer
All the given species (I, II, III, IV) may exist as hydrated species.

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