Which of the following is incorrect ?

Options

A. Water is more polar than `H_2S`
B. `H_2O_2` is a planar molecule
C. Heavy water is produced by the exhaustive electrolysis of water made acidic
D. `H_2O_2` acts both as oxidising as well as reducing agent in acidic medium

Answer

To solve the question "Which of the following is incorrect?", we need to evaluate each of the statements provided.

### Step-by-Step Solution:

1. **Evaluate Statement 1: "Water is more polar than H2S."**
- Water (H2O) has a bent molecular geometry due to the two lone pairs on the oxygen atom. The oxygen atom is highly electronegative compared to sulfur (S) in H2S. This difference in electronegativity contributes to the polarity of the molecule.
- **Conclusion:** This statement is correct.

2. **Evaluate Statement 2: "H2O2 is a planar molecule."**
- Hydrogen peroxide (H2O2) has a non-planar, open book-like structure due to the presence of torsional strain and the arrangement of the atoms. The presence of lone pairs on the oxygen atoms also contributes to this non-planarity.
- **Conclusion:** This statement is incorrect.

3. **Evaluate Statement 3: "Heavy water is produced by the exhaustive hydrolysis of water made acidic."**
- Heavy water (D2O) is produced through the electrolysis of water, typically using a solution of NaOH (sodium hydroxide) to increase the efficiency of the process. This statement correctly describes the formation of heavy water.
- **Conclusion:** This statement is correct.

4. **Evaluate Statement 4: "H2O2 can act as both oxidizing as well as reducing agent in acidic medium."**
- Hydrogen peroxide (H2O2) can indeed act as both an oxidizing agent and a reducing agent. In acidic conditions, it can reduce to water (acting as an oxidizing agent) and can also oxidize to oxygen (acting as a reducing agent).
- **Conclusion:** This statement is correct.

### Final Answer:
The incorrect statement is **Statement 2: "H2O2 is a planar molecule."**

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