In X - H----Y , both X and Y are electronegative elements

Options

A. electron density on X will increase and on H will decrease
B. in both electron density will increase
C. in both electron density will decrease
D. on X electron density will decrease and on H increase

Explanation

To solve the question regarding the electron density in the compound X-H-Y, where both X and Y are electronegative elements, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Elements**: We have two electronegative elements, X and Y, and a hydrogen atom (H) bonded between them.

2. **Understanding Electronegativity**: Electronegativity is the tendency of an atom to attract electrons towards itself. In this case, since both X and Y are electronegative, they will attract electrons more strongly than hydrogen.

3. **Formation of Hydrogen Bond**: When hydrogen is bonded to an electronegative element, it can form a hydrogen bond with another electronegative element. In this case, the bond between H and X will be polar due to the difference in electronegativity.

4. **Electron Density Shift**: In the bond X-H, the shared pair of electrons will be pulled closer to the more electronegative atom, which is X. This means that the electron density around X will increase.

5. **Charge Distribution**: As the electron density shifts towards X, it will acquire a partial negative charge (δ-), while hydrogen, losing some electron density, will acquire a partial positive charge (δ+).

6. **Conclusion**: Therefore, the electron density on X increases, while the electron density on H decreases. The correct answer to the question is that the electron density on X increases and on H decreases.

### Final Answer:
- Electron density on X increases while electron density on H decreases.