Chlorine gas is dried over :

Answer

To solve the question "Chlorine gas is dried over:", we need to identify the appropriate drying agent for chlorine gas. Here’s a step-by-step solution:

### Step 1: Understanding the Properties of Chlorine Gas
Chlorine gas (Cl₂) is a greenish-yellow gas with a pungent odor. It is highly reactive and can react with many substances, including water and some drying agents.

**Hint:** Consider the reactivity of chlorine gas when selecting a drying agent.

### Step 2: Identifying Common Drying Agents
Common drying agents include concentrated sulfuric acid (H₂SO₄), calcium oxide (CaO), and sodium hydroxide (NaOH). Each of these agents has different properties and reactivities.

**Hint:** Recall the characteristics of each drying agent and their potential reactions with chlorine.

### Step 3: Evaluating the Drying Agents
- **Concentrated Sulfuric Acid (H₂SO₄)**: It is a strong dehydrating agent and does not react with chlorine gas.
- **Calcium Oxide (CaO)**: This can react with chlorine gas, forming calcium chloride (CaCl₂).
- **Sodium Hydroxide (NaOH)**: This can also react with chlorine gas, forming sodium chloride (NaCl) and sodium hypochlorite (NaOCl).
- **Hydrobromic Acid (HBr)**: This is not a drying agent and would react with chlorine gas.

**Hint:** Consider which agents can dry chlorine gas without undergoing a reaction.

### Step 4: Conclusion
The most suitable drying agent for chlorine gas is concentrated sulfuric acid (H₂SO₄) because it effectively removes moisture without reacting with chlorine.

**Final Answer:** Chlorine gas is dried over concentrated sulfuric acid (H₂SO₄).