Hydrogen bonds are formed in many compounds e.g. `H_(2)O`, HF, `NH_(3)`. The boiling point of such compounds depends to a extent on the strength of hydrogen bond and the number of hydrogen bonds. The correct decreasing order of the boiling points above compounds is

Options

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

Explanation

To determine the correct decreasing order of boiling points for the compounds H₂O, HF, and NH₃, we need to analyze the strength and number of hydrogen bonds formed in each compound.

### Step-by-Step Solution:

1. **Identify the Compounds and Their Hydrogen Bonding:**
- The compounds in question are water (H₂O), hydrogen fluoride (HF), and ammonia (NH₃).
- Each of these compounds can form hydrogen bonds due to the presence of hydrogen atoms bonded to highly electronegative atoms (O, F, N).

2. **Strength of Hydrogen Bonds:**
- The strength of hydrogen bonds varies based on the electronegativity of the atoms involved:
- HF has the strongest hydrogen bonds because fluorine is the most electronegative element.
- H₂O has strong hydrogen bonds as oxygen is also highly electronegative but less so than fluorine.
- NH₃ has the weakest hydrogen bonds among these three because nitrogen is less electronegative than both oxygen and fluorine.

3. **Number of Hydrogen Bonds:**
- Water (H₂O) can form four hydrogen bonds per molecule due to its bent structure and the presence of two lone pairs on oxygen.
- Hydrogen fluoride (HF) can form two hydrogen bonds per molecule (one with another HF molecule).
- Ammonia (NH₃) can form three hydrogen bonds per molecule, but the overall strength is lower than that of water and HF.

4. **Comparing Boiling Points:**
- The boiling point of a substance is influenced by both the strength and the number of hydrogen bonds.
- Given that water can form the most hydrogen bonds and has strong hydrogen bonding, it has the highest boiling point.
- HF, while having strong hydrogen bonds, has fewer hydrogen bonds than water, resulting in a lower boiling point.
- NH₃ has the weakest hydrogen bonds and fewer hydrogen bonds compared to water and HF, giving it the lowest boiling point.

5. **Conclusion:**
- Based on the analysis, the correct decreasing order of boiling points for the compounds is:
- H₂O > HF > NH₃

### Final Answer:
The correct decreasing order of boiling points is:
**H₂O > HF > NH₃**