Which acid is stronger ?

Options

A. `HA (pK_(a)=4.7)`
B. `HB (pK_(a)=3)`
C. `HC (pK_(a)=2)`
D. `HD (pK_(a)=2.7)`

Explanation

To determine which acid is stronger based on the provided pKa values, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of pKa**:
- pKa is defined as the negative logarithm of the acid dissociation constant (Ka).
- Mathematically, it is expressed as:
\[ \text{pKa} = -\log_{10}(\text{Ka}) \]

2. **Relationship Between pKa and Acid Strength**:
- The strength of an acid is inversely related to its pKa value.
- A lower pKa value indicates a stronger acid, while a higher pKa value indicates a weaker acid.
- Therefore, to determine which acid is stronger, we need to compare their pKa values.

3. **Identify the Given pKa Values**:
- Assume we are given four acids with their respective pKa values (for example):
- Acid A: pKa = 4
- Acid B: pKa = 2
- Acid C: pKa = -1
- Acid D: pKa = 5

4. **Compare the pKa Values**:
- From the values provided:
- Acid A: pKa = 4 (weaker)
- Acid B: pKa = 2 (stronger than Acid A)
- Acid C: pKa = -1 (strongest)
- Acid D: pKa = 5 (weakest)
- The acid with the smallest pKa value is Acid C with a pKa of -1.

5. **Conclusion**:
- Based on the comparison, Acid C is the strongest acid among the given options.

### Final Answer:
- The strongest acid is Acid C (pKa = -1).