Which of the following has highest melting point

Options

A. `BaCl_2`
B. `MgCl_2`
C. `CaCl_2`
D. `BaCl_2`

Explanation

To determine which of the compounds (BECl2, MgCl2, CSCl2, and BaCl2) has the highest melting point, we need to analyze the ionic character and the strength of the bonds in each compound. Here's a step-by-step solution:

### Step 1: Identify the nature of the compounds
- **BECl2 (Beryllium chloride)**: Beryllium is a small, highly charged cation, which tends to form covalent bonds but can exhibit some ionic character due to its high charge density.
- **MgCl2 (Magnesium chloride)**: Magnesium is also a cation, but it is larger than beryllium and has a higher metallic character, leading to a more ionic bond with chloride ions.
- **CSCl2 (Carbon disulfide)**: This compound is primarily covalent due to the nature of carbon and sulfur.
- **BaCl2 (Barium chloride)**: Barium is a larger cation compared to magnesium and beryllium, leading to a more ionic character in its bond with chloride ions.

### Step 2: Compare the ionic character
- The ionic character of a compound generally increases with the difference in electronegativity between the cation and anion.
- Beryllium (Be) has the highest charge density, followed by magnesium (Mg), then barium (Ba). Carbon (C) has a very low ionic character in comparison to these metals.

### Step 3: Assess the melting points based on ionic character
- Compounds with higher ionic character typically have higher melting points due to the stronger electrostatic forces between the ions.
- Since BECl2 has the highest ionic character due to the high charge density of beryllium, it is expected to have the highest melting point among the options.

### Step 4: Conclusion
Based on the analysis, **BECl2** is expected to have the highest melting point due to its strong ionic character.

### Final Answer:
The compound with the highest melting point is **BECl2**.

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