Out of the following, amphiprotic species are `I. HPO_(3)^(2-)` II. `OH^(-)` III. `H_(2)PO_(4)^(-)` IV. `HCO_(3)^(-)`

Options

A. I, III, IV
B. I and III
C. III and IV
D. All

Answer

To determine which of the given species are amphiprotic, we need to analyze each species to see if they can both donate and accept protons (H⁺ ions). Amphiprotic species can act as either an acid (donating a proton) or a base (accepting a proton).

Let's evaluate each species one by one:

### Step 1: Evaluate HPO₃²⁻
- **Acidic Behavior**: HPO₃²⁻ can potentially donate a proton to form HPO₃³⁻, but it does not have any acidic protons left to donate further.
- **Basic Behavior**: It cannot accept a proton to form a stable species.
- **Conclusion**: HPO₃²⁻ is **not amphiprotic**.

### Step 2: Evaluate OH⁻
- **Acidic Behavior**: OH⁻ can accept a proton to form H₂O.
- **Basic Behavior**: It can theoretically donate a proton to form O²⁻, but O²⁻ is highly unstable.
- **Conclusion**: OH⁻ is **not amphiprotic**.

### Step 3: Evaluate H₂PO₄⁻
- **Acidic Behavior**: H₂PO₄⁻ can donate a proton to form HPO₄²⁻.
- **Basic Behavior**: It can accept a proton to form H₃PO₄.
- **Conclusion**: H₂PO₄⁻ is **amphiprotic**.

### Step 4: Evaluate HCO₃⁻
- **Acidic Behavior**: HCO₃⁻ can donate a proton to form CO₃²⁻.
- **Basic Behavior**: It can accept a proton to form H₂CO₃.
- **Conclusion**: HCO₃⁻ is **amphiprotic**.

### Final Conclusion
The amphiprotic species among the given options are:
- **III. H₂PO₄⁻**
- **IV. HCO₃⁻**

### Summary of Results
- **Amphiprotic Species**: H₂PO₄⁻ and HCO₃⁻
- **Not Amphiprotic**: HPO₃²⁻ and OH⁻