Which of the following is least ionic?

Options

A. AgCl
B. KCI
C. `BaCl_2`
D. `CoCl_2`.

Explanation

To determine which of the given compounds is the least ionic, we need to analyze the ionic character of each compound based on the elements involved and their positions in the periodic table. The compounds provided are:

1. AgCl (Silver Chloride)
2. KCl (Potassium Chloride)
3. BaCl2 (Barium Chloride)
4. CoCl2 (Cobalt(II) Chloride)

### Step-by-Step Solution:

**Step 1: Understand Ionic Bonding**
Ionic bonds form between metals (which lose electrons) and nonmetals (which gain electrons). The greater the difference in electronegativity between the two elements, the more ionic the bond.

**Step 2: Identify the Elements and Their Positions**
- **Ag (Silver)**: Transition metal
- **K (Potassium)**: Alkali metal (Group 1)
- **Ba (Barium)**: Alkaline earth metal (Group 2)
- **Co (Cobalt)**: Transition metal

**Step 3: Determine Electronegativity Values**
- **Electronegativity of Chlorine (Cl)**: 3.16 (highly electronegative)
- **Electronegativity of Silver (Ag)**: 1.93
- **Electronegativity of Potassium (K)**: 0.82
- **Electronegativity of Barium (Ba)**: 0.89
- **Electronegativity of Cobalt (Co)**: 1.88

**Step 4: Calculate the Difference in Electronegativity**
- For **AgCl**: |3.16 - 1.93| = 1.23
- For **KCl**: |3.16 - 0.82| = 2.34
- For **BaCl2**: |3.16 - 0.89| = 2.27
- For **CoCl2**: |3.16 - 1.88| = 1.28

**Step 5: Compare the Differences**
The compound with the smallest difference in electronegativity will be the least ionic:
- AgCl: 1.23
- KCl: 2.34
- BaCl2: 2.27
- CoCl2: 1.28

**Step 6: Conclusion**
The compound with the least ionic character is **AgCl** (Silver Chloride) since it has the smallest difference in electronegativity.

### Final Answer:
**AgCl (Silver Chloride) is the least ionic.**

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