Four species are listed below:
(`i`) `HCO_(3)^(-)`
(`ii`) `H_(3)O^(+)`
(`iii`) `HSO_(4)^(-)`
(`iv`) `HSO_(3)F`
Which one of the following is the correct sequence of their acid strength?

Options

A. `iv lt ii lt iii lt i`
B. `ii lt iii lt i lt iv`
C. `i lt iii lt ii lt iv`
D. `iii lt i lt iv lt ii`

Explanation

To determine the correct sequence of acid strength for the given species, we need to analyze their ability to donate protons (H⁺) based on their pKa values. The lower the pKa value, the stronger the acid.

### Step-by-Step Solution:

1. **Identify the Species and Their pKa Values:**
- **HCO₃⁻ (Bicarbonate):** pKa ≈ 10.24
- **H₃O⁺ (Hydronium Ion):** pKa ≈ -1.74
- **HSO₄⁻ (Hydrogen Sulfate):** pKa ≈ 1.94
- **HSO₃F (Fluorosulfuric Acid):** pKa ≈ -15

2. **Rank the Acids Based on Their pKa Values:**
- The species with the lowest pKa value is the strongest acid.
- From the values:
- HSO₃F: pKa = -15 (strongest acid)
- H₃O⁺: pKa = -1.74
- HSO₄⁻: pKa = 1.94
- HCO₃⁻: pKa = 10.24 (weakest acid)

3. **Establish the Sequence of Acid Strength:**
- Based on the pKa values, the order of acid strength from strongest to weakest is:
- HSO₃F > H₃O⁺ > HSO₄⁻ > HCO₃⁻

4. **Conclusion:**
- The correct sequence of acid strength is:
- **HSO₃F > H₃O⁺ > HSO₄⁻ > HCO₃⁻**

### Final Answer:
The correct sequence of their acid strength is: **HSO₃F > H₃O⁺ > HSO₄⁻ > HCO₃⁻**