One of the following is an incorrect statement. Point out the incorrect one.

Options

A. `H_(2)O_(2)`decomposes rapidely in presence of `MnO_(2)`
B. Ice at its melting point is lighter than water because ice crystals have hollow hexagonal arrangement of `H_(2)O` molecules.
C. `D_(2)O` will have maximum density at `11.5^(@)C`.
D. Water gas contains greater proportion of CO than that of `H_(2)`

Explanation

To identify the incorrect statement among the given options regarding hydrogen and its compounds, we can analyze each statement one by one.

### Step-by-Step Solution:

1. **Analyze Statement 1**: "H2O2 decomposes rapidly in presence of MnO2."
- Hydrogen peroxide (H2O2) does decompose into water (H2O) and oxygen (O2) when catalyzed by manganese dioxide (MnO2). This statement is **correct**.

2. **Analyze Statement 2**: "Ice at its melting point is lighter than water because ice crystals have hollow hexagonal arrangement of H2O molecules."
- Ice has a hexagonal crystalline structure, which makes it less dense than liquid water. This is why ice floats on water. This statement is also **correct**.

3. **Analyze Statement 3**: "DTO will have maximum density at 11.5 degrees Celsius."
- Deuterium oxide (DTO), also known as heavy water, does indeed have a maximum density at approximately 11.5 degrees Celsius. This statement is **correct**.

4. **Analyze Statement 4**: "Water gas contains greater proportion of CO than that of hydrogen."
- Water gas is a mixture of carbon monoxide (CO) and hydrogen (H2) produced by the reaction of steam with carbon. The typical composition of water gas is about equal parts of CO and H2, but it does not contain a greater proportion of CO than H2. This statement is **incorrect**.

### Conclusion:
The incorrect statement among the options provided is the fourth one: "Water gas contains greater proportion of CO than that of hydrogen."

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