Bromine is commercially prepared from sea water by displacement reaction
`Cl_(2)+2Br^(-)(aq.)to2Cl^(-)(aq.)+Br_(2)`
`Br_(2)` gas thus formed is dissolved into solution of `Na_(2)CO_(3)` and then pure `Br_(2)` iis obtained by treatment of the solution with :

Options

A. `Ca(OH)_(2)`
B. `NaOH`
C. `H_(2)SO_(4)`
D. `HI`

Explanation

To solve the problem, we need to understand the steps involved in obtaining pure bromine from the reaction of bromine with sodium carbonate, followed by treatment with a specific reagent. Here’s a step-by-step breakdown of the solution:

### Step 1: Identify the Initial Reaction
The initial reaction involves the displacement of bromide ions by chlorine gas. The reaction is:
\[ \text{Cl}_2 + 2 \text{Br}^- \rightarrow 2 \text{Cl}^- + \text{Br}_2 \]
This indicates that bromine gas (\( \text{Br}_2 \)) is produced from seawater.

**Hint**: Remember that displacement reactions involve one element being replaced by another in a compound.

### Step 2: Dissolve Bromine in Sodium Carbonate
The bromine gas produced is then dissolved in a hot aqueous solution of sodium carbonate (\( \text{Na}_2\text{CO}_3 \)). The reaction that occurs is:
\[ \text{Br}_2 + \text{Na}_2\text{CO}_3 \rightarrow \text{NaBr} + \text{NaBrO}_3 + \text{CO}_2 \]
This reaction produces sodium bromide (\( \text{NaBr} \)), sodium bromate (\( \text{NaBrO}_3 \)), and carbon dioxide (\( \text{CO}_2 \)).

**Hint**: Focus on the products formed when bromine reacts with sodium carbonate.

### Step 3: Heating with Sulfuric Acid
To obtain pure bromine gas from the sodium bromide, we treat it with sulfuric acid (\( \text{H}_2\text{SO}_4 \)). The reaction is:
\[ 2 \text{NaBr} + \text{H}_2\text{SO}_4 \rightarrow \text{Br}_2 + \text{Na}_2\text{SO}_4 + \text{H}_2\text{O} \]
This reaction produces pure bromine gas, sodium sulfate (\( \text{Na}_2\text{SO}_4 \)), and water.

**Hint**: Identify the role of sulfuric acid in converting sodium bromide to bromine gas.

### Step 4: Conclusion
From the above reactions, we conclude that the reagent needed to obtain pure bromine from the solution of sodium carbonate is sulfuric acid (\( \text{H}_2\text{SO}_4 \)).

**Final Answer**: The pure \( \text{Br}_2 \) is obtained by treatment of the solution with \( \text{H}_2\text{SO}_4 \).