Comparatively low melting point and insolubility in water of `AlCl_(3)` is explained by ______rule .

Explanation

To solve the question regarding the comparatively low melting point and insolubility in water of AlCl₃, we can follow these steps:

### Step 1: Identify the Type of Compound
AlCl₃ (aluminum chloride) can be classified as either an ionic or covalent compound. To determine its nature, we need to analyze the ions involved.

### Step 2: Analyze the Ions
AlCl₃ consists of aluminum ions (Al³⁺) and chloride ions (Cl⁻). The aluminum ion has a +3 charge and is relatively small, while the chloride ion has a -1 charge and is relatively larger.

### Step 3: Apply Fajans' Rule
Fajans' Rule helps us predict whether a bond is more ionic or covalent based on the size and charge of the ions. According to this rule, if a cation is small and highly charged, and the anion is large, the bond tends to be more covalent.

### Step 4: Determine the Nature of the Bond in AlCl₃
In AlCl₃, the Al³⁺ ion is small and has a high charge, while the Cl⁻ ion is larger. This combination favors covalent character in the bond between Al and Cl.

### Step 5: Explain the Properties
Due to the covalent nature of the bonds in AlCl₃:
- The melting point is relatively low compared to typical ionic compounds, which have higher melting points due to strong ionic bonds.
- AlCl₃ is also insoluble in water, as covalent compounds generally have lower solubility in polar solvents like water compared to ionic compounds.

### Conclusion
Thus, the comparatively low melting point and insolubility in water of AlCl₃ is explained by **Fajans' Rule**.

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