Melting point is very high for

Options

A. KCl
B. KBr
C. KI
D. KF

Explanation

To determine which compound has the highest melting point among KCl, KBr, KI, and KF, we need to analyze the ionic character of each compound and how it relates to their melting points.

### Step-by-Step Solution:

1. **Understanding Ionic and Covalent Character**:
- Ionic compounds consist of positively and negatively charged ions. The strength of the ionic bond is influenced by the charges of the ions and their sizes. The greater the charge and the smaller the size of the ions, the stronger the ionic bond.
- Covalent character arises when there is some degree of sharing of electrons between the ions, which can occur due to polarization. Polarization is more significant when a small cation is paired with a large anion.

2. **Identifying the Cations and Anions**:
- In our case, all compounds have the same cation, K⁺. The anions are F⁻, Cl⁻, Br⁻, and I⁻.
- The sizes of the anions increase down the group: F⁻ < Cl⁻ < Br⁻ < I⁻.

3. **Analyzing Covalent Character**:
- According to Fajans' rules, a small cation (K⁺) and a large anion (I⁻) will lead to more covalent character due to polarization. Therefore, KI will have the highest covalent character.
- Conversely, KF, with the smallest anion (F⁻), will have the least covalent character and the highest ionic character.

4. **Relating Ionic Character to Melting Point**:
- Higher ionic character corresponds to stronger ionic bonds, which require more energy to break. Thus, compounds with higher ionic character will have higher melting points.
- Since KF has the highest ionic character among the given options, it will have the highest melting point.

5. **Conclusion**:
- Based on the analysis, the compound with the highest melting point is **KF**.

### Final Answer:
The melting point is very high for **KF**.