Which one of the following is a strong acid?

Options

A. `CH_(3)COOH`
B. HCl
C. `H_(2)C_(2)O_(4)`
D. `H_(2)CO_(3)`

Answer

To determine which one of the following is a strong acid among the options provided (acetic acid, hydrochloric acid, oxalic acid, and carbonic acid), we can follow these steps:

### Step 1: Understanding Strong Acids
Strong acids are substances that completely dissociate into their ions in an aqueous solution. This means that they release a high concentration of hydrogen ions (H⁺) when dissolved in water.

### Step 2: Analyzing the Given Options
We have four acids to consider:
1. **Acetic Acid (CH₃COOH)** - A weak acid that partially dissociates in solution.
2. **Hydrochloric Acid (HCl)** - A strong acid that completely dissociates in solution.
3. **Oxalic Acid (C₂H₂O₄)** - A weak acid that partially dissociates in solution.
4. **Carbonic Acid (H₂CO₃)** - A weak acid that partially dissociates in solution.

### Step 3: Comparing the Acids
- **Acetic Acid**: It has a conjugate base (CH₃COO⁻) that is relatively stable but does not dissociate completely, making it a weak acid.
- **Hydrochloric Acid**: It has a conjugate base (Cl⁻) that is highly stable due to its high electronegativity and complete dissociation, making it a strong acid.
- **Oxalic Acid**: Its conjugate base (HC₂O₄⁻) is less stable, indicating that it does not dissociate completely, thus it is a weak acid.
- **Carbonic Acid**: Its conjugate base (HCO₃⁻) is also less stable, indicating partial dissociation, making it a weak acid.

### Step 4: Conclusion
Among the four acids, **Hydrochloric Acid (HCl)** is the only strong acid as it completely dissociates in solution and has the most stable conjugate base (Cl⁻).

### Final Answer
The strong acid among the options is **Hydrochloric Acid (HCl)**.

---