Write the correct order of acidic strength of following compounds:
`(a)H - F " "(b) H - Cl`
`(c) H - Br" "(d)H - I `

Answer

To determine the correct order of acidic strength for the compounds \( H-F \), \( H-Cl \), \( H-Br \), and \( H-I \), we can follow these steps:

### Step 1: Identify the Conjugate Bases
When an acid donates a proton (\( H^+ \)), it forms a conjugate base. For each of the acids given, the conjugate bases are:
- For \( H-F \): The conjugate base is \( F^- \)
- For \( H-Cl \): The conjugate base is \( Cl^- \)
- For \( H-Br \): The conjugate base is \( Br^- \)
- For \( H-I \): The conjugate base is \( I^- \)

### Step 2: Assess the Stability of the Conjugate Bases
The strength of an acid is related to the stability of its conjugate base. A more stable conjugate base corresponds to a stronger acid. The stability of the conjugate bases can be influenced by the size of the atoms and the ability to disperse the negative charge.

- \( F^- \) (Fluoride) is the smallest and least stable due to high electronegativity and small size.
- \( Cl^- \) (Chloride) is larger than \( F^- \) and more stable.
- \( Br^- \) (Bromide) is larger than \( Cl^- \) and even more stable.
- \( I^- \) (Iodide) is the largest and most stable due to the ability to disperse the negative charge over a larger volume.

### Step 3: Determine the Order of Acidity
Based on the stability of the conjugate bases:
- \( I^- \) is the most stable, so \( H-I \) is the strongest acid.
- \( Br^- \) is next, so \( H-Br \) follows.
- \( Cl^- \) is less stable than \( Br^- \), so \( H-Cl \) comes next.
- \( F^- \) is the least stable, making \( H-F \) the weakest acid.

### Conclusion: Order of Acidity
Thus, the correct order of acidic strength from strongest to weakest is:
\[ H-I > H-Br > H-Cl > H-F \]

### Final Answer
The order of acidic strength is:
1. \( H-I \)
2. \( H-Br \)
3. \( H-Cl \)
4. \( H-F \)