In the following, strongest acid is :

Options

A. `CH_3CH_2COOH`
B. `CH_3COOH `
C. `C_6 H_5 COOH `
D. `C_6H_5CH_2COOH`

Answer

To determine which of the given compounds is the strongest acid, we need to analyze how well each compound can donate a proton (H+) and how the resulting negative charge (conjugate base) can be stabilized. Here’s a step-by-step solution:

### Step 1: Identify the Compounds
First, we need to identify the four compounds given in the question. Let's assume they are:
1. Compound A
2. Compound B
3. Compound C
4. Compound D

### Step 2: Understand Acid Strength
The strength of an acid is determined by its ability to donate a proton (H+). When an acid donates a proton, it forms a conjugate base. The stability of this conjugate base is crucial; the more stable the conjugate base, the stronger the acid.

### Step 3: Analyze the Conjugate Bases
For each compound, we will analyze the structure of the conjugate base formed after the proton is lost.

- **Compound A**: After losing H+, the conjugate base will have a negative charge that may not be well stabilized.
- **Compound B**: Similar analysis as Compound A.
- **Compound C**: The conjugate base formed here will have a negative charge that can be stabilized by resonance or inductive effects.
- **Compound D**: The conjugate base may also have some stabilization, but it is less effective than in Compound C.

### Step 4: Evaluate Stabilization Effects
- **Inductive Effect**: The presence of electronegative atoms or groups can stabilize the negative charge through the inductive effect.
- **Resonance Effect**: If the negative charge can delocalize through resonance, this will significantly stabilize the conjugate base.

### Step 5: Compare the Compounds
- **Compound C**: If it has a phenyl group attached to the carboxyl group, the negative charge on the conjugate base can be stabilized by resonance with the phenyl ring, making it more stable.
- **Compound D**: If it lacks the resonance stabilization or has less effective inductive effects compared to Compound C, it will be a weaker acid.

### Conclusion
After analyzing all compounds, we conclude that **Compound C** is the strongest acid due to the resonance stabilization of its conjugate base.