Which of the following is the correct order of relative strength of acids ?

Options

A. `ClCH_(2)COOH gt BrCH_(2)COOH gt FCH_(2)COOH`
B. `BrCH_(2)COOH gt ClCH_(2)COOH gt FCH_(2)COOH`
C. `FCH_(2)COOH gt ClCH_(2)COOH gt BrCH_(2)COOH`
D. `ClCH_(2)COOH gt FCH_(2)COOH gt BrCH_(2)COOH`

Explanation

To determine the correct order of relative strength of acids among the given derivatives of acetic acid (CH3COOH), we can analyze the effects of the substituents (F, Cl, Br) on the acidity. Here’s a step-by-step solution:

### Step 1: Identify the Acidic Compounds
We are given derivatives of acetic acid where the hydrogen atom is replaced by F (fluorine), Cl (chlorine), and Br (bromine). The compounds can be represented as:
- CH2FCOOH (Fluoroacetic acid)
- CH2ClCOOH (Chloroacetic acid)
- CH2BrCOOH (Bromoacetic acid)

### Step 2: Understand the Effects of Substituents
The acidity of an acid is influenced by the substituents attached to its structure. The presence of electronegative atoms (like F, Cl, Br) can affect the stability of the conjugate base formed after deprotonation.

- **Inductive Effect (−I Effect)**: Electronegative atoms pull electron density away from the rest of the molecule, stabilizing the negative charge on the conjugate base.
- **Order of Electronegativity**: F > Cl > Br. This means that fluorine has the strongest −I effect, followed by chlorine, and then bromine.

### Step 3: Analyze the Acidity
Since the −I effect increases the acidity of the acids, we can conclude:
- The acid with fluorine (CH2FCOOH) will be the strongest acid because fluorine has the strongest −I effect.
- The acid with chlorine (CH2ClCOOH) will be the second strongest.
- The acid with bromine (CH2BrCOOH) will be the weakest among these three.

### Step 4: Establish the Order of Acidity
Based on the analysis above, we can establish the order of acidity as follows:
1. CH2FCOOH (Fluoroacetic acid) - Strongest
2. CH2ClCOOH (Chloroacetic acid) - Second strongest
3. CH2BrCOOH (Bromoacetic acid) - Weakest

### Final Order
Thus, the correct order of relative strength of acids is:
**CH2FCOOH > CH2ClCOOH > CH2BrCOOH**