Identify the correct formula of halides of alkaline earth metals from the following.

Options

A. `BaCI_(2).2H_(2)O`
B. `BaCI_(2).4H_(2)O`
C. `CaCI_(2).6H_(2)O`
D. `SrCI_(2).4H_(2)O`

Explanation

To identify the correct formula of halides of alkaline earth metals, we need to analyze the options given and understand the general properties of these compounds. Here’s a step-by-step solution:

### Step 1: Understand the Alkaline Earth Metals
Alkaline earth metals include beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba). They typically form halides with halogens (F, Cl, Br, I).

### Step 2: Recognize the General Formula of Halides
The general formula for the halides of alkaline earth metals is \( MCl_2 \), where \( M \) represents the alkaline earth metal. This is because alkaline earth metals have a +2 oxidation state.

### Step 3: Identify the Hydration of Halides
Alkaline earth metal halides are known to be hygroscopic, meaning they can absorb moisture from the air. The extent of hydration varies among the metals:
- Magnesium can accommodate up to 6 water molecules.
- Calcium can also accommodate 6 water molecules.
- Strontium can accommodate 2 water molecules.
- Barium can accommodate 2 water molecules.

### Step 4: Write the Correct Formulas
Based on the above information, we can write the formulas for the halides of alkaline earth metals with their respective water of crystallization:
- Magnesium Chloride: \( MgCl_2 \cdot 6H_2O \)
- Calcium Chloride: \( CaCl_2 \cdot 6H_2O \)
- Strontium Chloride: \( SrCl_2 \cdot 2H_2O \)
- Barium Chloride: \( BaCl_2 \cdot 2H_2O \)

### Step 5: Analyze the Options
Now, we can analyze the options provided in the question:
- Option A: \( BaCl_2 \) (Correct)
- Option B: \( CaCl_2 \cdot H_2O \) (Incorrect, should be \( CaCl_2 \cdot 6H_2O \))
- Option C: \( SrCl_2 \cdot 2H_2O \) (Correct)
- Option D: \( MgCl_2 \cdot 2H_2O \) (Incorrect, should be \( MgCl_2 \cdot 6H_2O \))

### Conclusion
From the analysis, the correct formulas of halides of alkaline earth metals are:
- \( BaCl_2 \)
- \( SrCl_2 \cdot 2H_2O \)

Thus, the correct answers are options A and C.

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