Hydrogen bromide is dried by passing the gas through:

Options

A. (A) quick line
B. anhydrous calcium chloride
C. (C) potassium hydroxide pellet
D. (D)con. `H2SO_4`

Answer

To solve the question regarding how to dry hydrogen bromide (HBr), we can follow these steps:

### Step 1: Understand the properties of Hydrogen Bromide
Hydrogen bromide is a colorless gas that is highly soluble in water. It is important to note that when we want to dry a gas, we need to use a drying agent that can absorb moisture without reacting with the gas itself.

### Step 2: Identify the drying agents from the options provided
The options given are:
1. Quicklime (Calcium Oxide, CaO)
2. Anhydrous Calcium Chloride (CaCl2)
3. Potassium Hydroxide (KOH)
4. Concentrated Sulfuric Acid (H2SO4)

### Step 3: Evaluate each option
- **Quicklime (CaO)**: This is primarily used to absorb water but may not be effective for drying gases like HBr.
- **Anhydrous Calcium Chloride (CaCl2)**: This is a well-known drying agent that can absorb moisture and is effective for drying gases.
- **Potassium Hydroxide (KOH)**: While it can absorb moisture, it reacts with acids, including HBr, which makes it unsuitable for drying HBr.
- **Concentrated Sulfuric Acid (H2SO4)**: This is also a strong dehydrating agent but can react with HBr, making it unsuitable as well.

### Step 4: Conclusion
The most suitable drying agent for hydrogen bromide from the options provided is **Anhydrous Calcium Chloride (CaCl2)**.

### Final Answer
Hydrogen bromide is dried by passing the gas through **Anhydrous Calcium Chloride (Option B)**.

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