Which of the following are good conductors of electricity in the molten state?

Options

A. `BeCl_(2)`
B. `CaCl_(2)`
C. `SrCl_(2)`
D. `MgCl_(2)`

Answer

To determine which of the given compounds are good conductors of electricity in the molten state, we can follow these steps:

### Step 1: Identify the Compounds
The compounds given are:
- BaCl2 (Barium chloride)
- CaCl2 (Calcium chloride)
- SrCl2 (Strontium chloride)
- MgCl2 (Magnesium chloride)

### Step 2: Understand the Concept of Electrical Conductivity
Electrical conductivity in molten state depends on the presence of free-moving charged particles, specifically ions. In the molten state, ionic compounds dissociate into their respective ions, which can move freely and conduct electricity.

### Step 3: Analyze the Ionic Character
The ionic character of the compounds increases as we move down the group in the periodic table. This is because the size of the metal ion increases, leading to a greater ability to form free ions in the molten state.

### Step 4: Evaluate Each Compound
- **BaCl2**: Barium chloride is expected to have a good ionic character and thus can conduct electricity in the molten state.
- **CaCl2**: Calcium chloride also has a good ionic character and can conduct electricity in the molten state.
- **SrCl2**: Strontium chloride, like the others, has a good ionic character and can conduct electricity in the molten state.
- **MgCl2**: Magnesium chloride has a significant ionic character and can conduct electricity in the molten state.

### Step 5: Identify the Exception
- **BeCl2**: Beryllium chloride is more covalent in nature compared to the others due to the small size of the Be2+ ion, which leads to a stronger covalent character. Therefore, it does not dissociate into free ions in the molten state and cannot conduct electricity effectively.

### Step 6: Conclusion
The compounds that are good conductors of electricity in the molten state are:
- CaCl2
- SrCl2
- MgCl2
- BaCl2

### Final Answer
The good conductors of electricity in the molten state are **CaCl2, SrCl2, MgCl2, and BaCl2**.

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