Which of the following order of H-bond strength is not correct :-

Options

A. `HF gt H_(2)O gt NH_(3) gt H_(2)S`
B. `D_(2)O gt H_(2)O`
C. `H_(2)O gt H_(2)O_(2)`
D. `HF_(2)^(-) lt (HF)_(2)`

Explanation

To determine which order of hydrogen bond strength is not correct, we need to analyze the strength of hydrogen bonds in different compounds based on the electronegativity of the atoms involved. The compounds in question are:

1. HF (Hydrogen fluoride)
2. H2O (Water)
3. NH3 (Ammonia)
4. H2S (Hydrogen sulfide)

### Step 1: Understand the Electronegativity Trend
Electronegativity is the ability of an atom to attract electrons in a bond. The trend in electronegativity across the periodic table is that it increases from left to right and decreases from top to bottom. Therefore, the electronegativity order for the elements involved is:
- F > O > N > S

### Step 2: Analyze Hydrogen Bond Strength
Hydrogen bonds are stronger when the hydrogen is bonded to a more electronegative atom. Thus, the strength of hydrogen bonds in the given compounds can be ordered based on the electronegativity of the atoms bonded to hydrogen:
- HF (strongest)
- H2O (next strongest)
- NH3 (weaker than H2O)
- H2S (weakest)

### Step 3: Determine the Incorrect Order
Now, let's evaluate the proposed orders:
1. HF > H2O > NH3 > H2S (This order is correct)
2. D2O > H2O (This order is correct, as D2O has stronger hydrogen bonds due to the presence of deuterium)
3. H2O > H2O2 (This order is incorrect because H2O2 has more electronegative oxygen atoms contributing to stronger hydrogen bonding)
4. HF2- > HF2 (This order is correct, as the presence of a negative charge in HF2- can stabilize the hydrogen bond)

### Conclusion
The incorrect order of hydrogen bond strength is:
**H2O > H2O2**

### Final Answer
The answer is option C: H2O > H2O2 is the incorrect order of hydrogen bond strength.

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