On moving from left to right in a period what is the order of acidic character of hydrides ?

Options

A. `NH_(3) lt H_(2)O lt HF`
B. `HF lt H_(2)O lt NH_(3)`
C. `H_(2)O lt HF lt NH_(3)`
D. `H_(2)O lt NH_(3) lt HF`

Explanation

To determine the order of acidic character of hydrides as we move from left to right in a period, we will analyze the hydrides of nitrogen (NH3), oxygen (H2O), and fluorine (HF). The acidic character of these hydrides is related to their ability to donate a proton (H⁺) and the stability of their conjugate bases after the proton is removed.

### Step-by-Step Solution:

1. **Identify the Hydrides**: We are considering the hydrides of nitrogen (NH3), oxygen (H2O), and fluorine (HF).

2. **Understanding Acidic Character**: The acidic character of a compound is defined by its ability to donate a proton (H⁺). The more stable the conjugate base formed after the donation of H⁺, the stronger the acid.

3. **Conjugate Bases Formation**:
- For NH3 (ammonia), the conjugate base formed is NH2⁻ (amide ion).
- For H2O (water), the conjugate base formed is OH⁻ (hydroxide ion).
- For HF (hydrofluoric acid), the conjugate base formed is F⁻ (fluoride ion).

4. **Stability of Conjugate Bases**: The stability of the conjugate bases is influenced by the electronegativity of the atoms involved:
- F⁻ is more stable due to fluorine's high electronegativity.
- OH⁻ is less stable than F⁻ but more stable than NH2⁻.
- NH2⁻ is the least stable among the three.

5. **Order of Stability of Conjugate Bases**: Based on the stability of the conjugate bases:
- F⁻ > OH⁻ > NH2⁻

6. **Order of Acidic Character**: Since the acidic strength is directly proportional to the stability of the conjugate base, we can conclude:
- HF > H2O > NH3

### Final Answer:
The order of acidic character of the hydrides from left to right in the period is:
**HF > H2O > NH3**