The correct order of ionic character of oxides of alkali earth metal:-

Options

A. `MgO gt CaO gt SrO gt BaO`
B. `BaO gt SrO gt CaO gt MgO`
C. `CaO gt SrO gt BaO gt MgO`
D. `SrO gt BaO gt MgO gt CaO`

Explanation

To determine the correct order of ionic character of the oxides of alkali earth metals, we can follow these steps:

### Step 1: Identify the Alkali Earth Metals
The alkali earth metals are located in Group 2 of the periodic table. The relevant metals for this question are:
- Magnesium (Mg)
- Calcium (Ca)
- Strontium (Sr)
- Barium (Ba)

### Step 2: Understand Ionic Character
Ionic character refers to the extent to which a compound exhibits ionic properties. According to Fajans' rules, the ionic character of a bond increases with the size of the cation. Larger cations tend to polarize the electron cloud of the anion more effectively, leading to a greater ionic character.

### Step 3: Analyze Cation Size
As we move down the group in the periodic table, the size of the cations increases:
- Magnesium (Mg²⁺) is the smallest cation.
- Calcium (Ca²⁺) is larger than magnesium.
- Strontium (Sr²⁺) is larger than calcium.
- Barium (Ba²⁺) is the largest cation.

### Step 4: Determine the Order of Ionic Character
Since the ionic character increases with the size of the cation, we can arrange the oxides of these metals in order of increasing ionic character:
- Magnesium oxide (MgO) will have the lowest ionic character.
- Calcium oxide (CaO) will have a higher ionic character than MgO.
- Strontium oxide (SrO) will have a higher ionic character than CaO.
- Barium oxide (BaO) will have the highest ionic character.

### Step 5: Write the Final Order
Thus, the correct order of ionic character of the oxides of alkali earth metals is:
\[ \text{BaO} > \text{SrO} > \text{CaO} > \text{MgO} \]

### Conclusion
The correct answer, based on the analysis, is that the ionic character of the oxides of alkali earth metals increases from magnesium oxide to barium oxide.