Write the correct order of acidic strength of following compounds:
`(a)F - CH_(2) - CH_(2) - O-H" "(b) NO_(2)- CH_(2)-CH_(2)-O-H`
`(c) Br - CH_(2) - CH_(2) - O-H" "(d) overset(o+)(NH_(3))- CH_(2) - CH_(2) -O - H `

Answer

To determine the correct order of acidic strength for the given compounds, we need to analyze the stability of the conjugate bases formed after the loss of a proton (H⁺) from each compound. The more stable the conjugate base, the stronger the acid.

### Step-by-Step Solution:

1. **Identify the Compounds**:
- (a) F - CH₂ - CH₂ - OH
- (b) NO₂ - CH₂ - CH₂ - OH
- (c) Br - CH₂ - CH₂ - OH
- (d) NH₃⁺ - CH₂ - CH₂ - OH

2. **Understand the Acidic Strength**:
- Acids release H⁺ ions, resulting in the formation of conjugate bases. The stability of these conjugate bases is crucial in determining the acidic strength.
- A more stable conjugate base corresponds to a stronger acid.

3. **Analyze Each Compound**:
- **Compound (a)**: F - CH₂ - CH₂ - O⁻
- The fluorine atom is highly electronegative and exerts a strong -I (inductive) effect, stabilizing the negative charge on the conjugate base.

- **Compound (b)**: NO₂ - CH₂ - CH₂ - O⁻
- The nitro group (NO₂) is a very strong electron-withdrawing group and stabilizes the negative charge significantly due to resonance and inductive effects.

- **Compound (c)**: Br - CH₂ - CH₂ - O⁻
- Bromine is less electronegative than fluorine and has a weaker -I effect compared to the nitro group, thus providing less stabilization to the negative charge.

- **Compound (d)**: NH₃⁺ - CH₂ - CH₂ - O⁻
- The positive charge on the nitrogen enhances its electron-withdrawing ability, making this compound's conjugate base very stable due to the strong -I effect from the positively charged nitrogen.

4. **Determine the Order of Stability**:
- The stability of the conjugate bases can be ranked based on the strength of the electron-withdrawing groups:
- (d) NH₃⁺ - CH₂ - CH₂ - O⁻ (most stable)
- (b) NO₂ - CH₂ - CH₂ - O⁻
- (a) F - CH₂ - CH₂ - O⁻
- (c) Br - CH₂ - CH₂ - O⁻ (least stable)

5. **Final Order of Acidic Strength**:
- The order of acidic strength from strongest to weakest is:
- (d) > (b) > (a) > (c)

### Conclusion:
The correct order of acidic strength for the given compounds is:
**(d) > (b) > (a) > (c)**