Dehydration of hydrates of halides of calcium, barium and strontium i.e., `CaCI_(2). 6H_(2)O, BaCI_(2).2H_(2)O, SrCI_(2).2H_(2)O`, can be achieved by heating. These become wet on keeping in air. Which of the following statements is correct about these halides?

Options

A. Act as dehydrating agent
B. Can absorb moisture from air
C. Tendency to form hydrate decreases from calcium to barium
D. All of the above

Explanation

To solve the question regarding the dehydration of hydrates of halides of calcium, barium, and strontium, let's break it down step by step:

### Step 1: Understanding the Compounds
The compounds in question are:
- Calcium chloride hexahydrate: \( \text{CaCl}_2 \cdot 6\text{H}_2\text{O} \)
- Barium chloride dihydrate: \( \text{BaCl}_2 \cdot 2\text{H}_2\text{O} \)
- Strontium chloride dihydrate: \( \text{SrCl}_2 \cdot 2\text{H}_2\text{O} \)

These compounds contain water of crystallization, which can be removed by heating.

### Step 2: Dehydration Process
When these hydrates are heated, they lose their water molecules:
- \( \text{CaCl}_2 \cdot 6\text{H}_2\text{O} \) becomes \( \text{CaCl}_2 \) (anhydrous)
- \( \text{BaCl}_2 \cdot 2\text{H}_2\text{O} \) becomes \( \text{BaCl}_2 \) (anhydrous)
- \( \text{SrCl}_2 \cdot 2\text{H}_2\text{O} \) becomes \( \text{SrCl}_2 \) (anhydrous)

### Step 3: Hygroscopic Nature
The question states that these compounds become wet when kept in air. This is due to their hygroscopic nature, which means they can absorb moisture from the atmosphere.

### Step 4: Correct Statements
Now, we need to evaluate the statements about these halides:
1. They are dehydrating agents and can absorb moisture from the air.
2. The tendency to form hydrates decreases from calcium to barium.

Both statements are correct:
- The first statement is true because these compounds can absorb water from the air.
- The second statement is also true because the ability to form hydrates decreases as we move down the group from calcium to barium due to decreasing hydration energy.

### Conclusion
Thus, both statements about the halides are correct.

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