Compound `XY` is predominantly ionic as `X^(o+)Y^(ɵ)` if

Options

A. `(IE)_(X) lt (IE)_(Y)`
B. `(EA)_(X) lt (EA)_(Y)`
C. `(EN)_(X) lt (EN)_(Y)`
D. `(IE)_Y) lt (IE)_(X)`.

Explanation

To determine the conditions under which the compound XY is predominantly ionic, we need to analyze the properties of the elements X and Y based on their electronegativity, ionization energy, and electron affinity. Here’s a step-by-step solution:

### Step-by-Step Solution:

1. **Understanding Ionic Compounds**:
- Ionic compounds are formed between metals and non-metals. Metals tend to lose electrons and form cations, while non-metals tend to gain electrons and form anions.

2. **Electronegativity Difference**:
- The ionic character of a bond is significantly influenced by the difference in electronegativity (ΔEN) between the two elements. A larger difference in electronegativity typically indicates a more ionic character.
- For compound XY to be predominantly ionic, element X (the metal) should have a lower electronegativity than element Y (the non-metal).

3. **Analyzing the Options**:
- **Option 1: IE of X < IE of Y**: This suggests that X can lose electrons more easily than Y, which is favorable for ionic bond formation but does not directly indicate the ionic nature.
- **Option 2: EA of X = EA of Y**: This indicates that the electron affinity of both elements is the same, which does not support the formation of an ionic bond.
- **Option 3: EN of X < EN of Y**: This is the most crucial condition. If the electronegativity of X is less than that of Y, then X can effectively lose electrons to Y, leading to the formation of cations and anions, hence forming an ionic bond.
- **Option 4: IE of Y < IE of X**: This suggests that Y can lose electrons more easily than X, which contradicts the typical behavior of non-metals.

4. **Conclusion**:
- The correct condition for compound XY to be predominantly ionic is that the electronegativity of X is less than that of Y (Option 3). This means that X is a metal and Y is a non-metal, facilitating the formation of an ionic bond.

### Final Answer:
The correct answer is **Option 3: EN of X < EN of Y**.