The covalent characters of `CaCl_2 BaCl_2, SrCl_2` and `MgCl_2` follow the order :

Options

A. `CaCl_2 lt BaCl_2 lt SrCl_2 lt MgCl_2`
B. `BaCl_2 lt SrCl_2 lt CaCl_2 lt MgCl_2`
C. `CaCl_2 lt BaCl_2 lt MgCl_2 lt SrCl_2`
D. `SrCl_2 lt MgCl_2 lt CaCl_2 lt BaCl_2`

Explanation

To determine the order of covalent character among the compounds \( \text{CaCl}_2, \text{BaCl}_2, \text{SrCl}_2, \text{MgCl}_2 \), we can follow these steps:

### Step 1: Understand the Concept of Covalent and Ionic Character
Covalent character refers to the extent to which a compound exhibits covalent bonding as opposed to ionic bonding. Generally, compounds with higher ionic character will have lower covalent character and vice versa.

### Step 2: Identify the Group and Period of Elements
The compounds given are chlorides of the alkaline earth metals (Group 2 elements):
- Magnesium (\( \text{Mg} \)) - Period 3
- Calcium (\( \text{Ca} \)) - Period 4
- Strontium (\( \text{Sr} \)) - Period 5
- Barium (\( \text{Ba} \)) - Period 6

### Step 3: Analyze the Metallic Character
As we move down the group from magnesium to barium, the metallic character increases. This is because the outer electrons are further from the nucleus and are more easily lost.

### Step 4: Determine Ionic Character
With increasing metallic character, the ionic character of the chlorides also increases. Therefore, the order of ionic character from highest to lowest is:
- \( \text{MgCl}_2 \) (most ionic)
- \( \text{CaCl}_2 \)
- \( \text{SrCl}_2 \)
- \( \text{BaCl}_2 \) (least ionic)

### Step 5: Establish the Covalent Character Order
Since covalent character is inversely related to ionic character, we can establish the order of covalent character as:
- \( \text{BaCl}_2 \) (most covalent)
- \( \text{SrCl}_2 \)
- \( \text{CaCl}_2 \)
- \( \text{MgCl}_2 \) (least covalent)

### Final Order of Covalent Character
Thus, the final order of covalent character is:
\[ \text{BaCl}_2 > \text{SrCl}_2 > \text{CaCl}_2 > \text{MgCl}_2 \]