Which of the following given below can liberate `Br_(2)` from `KBr`?
`F_(2),Cl_(2),I_(2) and " Conc. "H_(2)SO_(4)`

Options

A. `F_(2), Cl_(2), I_(2) and "Conc. "H_(2)SO_(4)`
B. `Cl_(2), I_(2) and "Conc. "H_(2)SO_(4)`
C. `F_(2),Cl_(2), I_(2)`
D. `F_(2),Cl_(2) and "Conc. "H_(2)SO_(4)`

Answer

To determine which of the given substances can liberate \( \text{Br}_2 \) from \( \text{KBr} \), we need to analyze the oxidizing strength of each substance in relation to bromine. The substances provided are \( \text{F}_2 \), \( \text{Cl}_2 \), \( \text{I}_2 \), and concentrated \( \text{H}_2\text{SO}_4 \).

### Step-by-Step Solution:

1. **Identify the Oxidizing Agents**:
- \( \text{F}_2 \) (Fluorine) is a strong oxidizing agent.
- \( \text{Cl}_2 \) (Chlorine) is also a strong oxidizing agent.
- \( \text{I}_2 \) (Iodine) is a weaker oxidizing agent compared to \( \text{Br}_2 \).
- Concentrated \( \text{H}_2\text{SO}_4 \) can act as an oxidizing agent under certain conditions.

2. **Reactions with \( \text{KBr} \)**:
- **For \( \text{F}_2 \)**:
\[ \text{2KBr} + \text{F}_2 \rightarrow \text{2KF} + \text{Br}_2 \]
This shows that \( \text{F}_2 \) can liberate \( \text{Br}_2 \) from \( \text{KBr} \).

- **For \( \text{Cl}_2 \)**:
\[ \text{2KBr} + \text{Cl}_2 \rightarrow \text{2KCl} + \text{Br}_2 \]
This indicates that \( \text{Cl}_2 \) can also liberate \( \text{Br}_2 \) from \( \text{KBr} \).

- **For \( \text{I}_2 \)**:
- Since \( \text{I}_2 \) is a weaker oxidizing agent than \( \text{Br}_2 \), it cannot liberate \( \text{Br}_2 \) from \( \text{KBr} \).

- **For Concentrated \( \text{H}_2\text{SO}_4 \)**:
- When concentrated \( \text{H}_2\text{SO}_4 \) reacts with \( \text{KBr} \), it can produce \( \text{HBr} \), which can then reduce the sulfuric acid:
\[ \text{2KBr} + \text{H}_2\text{SO}_4 \rightarrow \text{K}_2\text{SO}_4 + \text{2HBr} \]
\[ \text{2HBr} + \text{H}_2\text{SO}_4 \rightarrow \text{SO}_2 + \text{Br}_2 + \text{2H}_2\text{O} \]
This shows that concentrated \( \text{H}_2\text{SO}_4 \) can also liberate \( \text{Br}_2 \).

3. **Conclusion**:
- The substances that can liberate \( \text{Br}_2 \) from \( \text{KBr} \) are \( \text{F}_2 \), \( \text{Cl}_2 \), and concentrated \( \text{H}_2\text{SO}_4 \).

### Final Answer:
- The correct options are \( \text{F}_2 \), \( \text{Cl}_2 \), and concentrated \( \text{H}_2\text{SO}_4 \).