Which of the following statements is incorrect ?

Options

A. Natural gas is chiefly made of methane along with small proportions of butane and propane.
B. Producer gas is a mixture of carbon monoxide and nitrogen.
C. Water gas is a mixture of carbon monoxide and water.
D. Coal gas contains hydrogen, methane carbon monoxide and some other gases.

Explanation

To determine which statement is incorrect among the given options, let's analyze each statement one by one.

### Step 1: Analyze the First Statement
**Statement:** Natural gas is chiefly made of methane along with a small proportion of butane and propane.

- **Analysis:** This statement is correct. Natural gas primarily consists of methane (CH₄), and it may contain small amounts of other hydrocarbons like butane (C₄H₁₀) and propane (C₃H₈).

### Step 2: Analyze the Second Statement
**Statement:** Producer gas is a mixture of carbon monoxide and hydrogen gas.

- **Analysis:** This statement is also correct. Producer gas is indeed a mixture of carbon monoxide (CO) and hydrogen (H₂), along with some nitrogen (N₂).

### Step 3: Analyze the Third Statement
**Statement:** Water gas is a mixture of carbon monoxide and water.

- **Analysis:** This statement is incorrect. Water gas is actually a mixture of carbon monoxide (CO) and hydrogen gas (H₂), not water.

### Step 4: Analyze the Fourth Statement
**Statement:** Coal gas contains hydrogen, methane, carbon monoxide, and some other gases.

- **Analysis:** This statement is correct. Coal gas is a mixture that includes hydrogen (H₂), methane (CH₄), carbon monoxide (CO), and other gases.

### Conclusion
After analyzing all the statements, we find that the **third statement** is incorrect.

### Final Answer
The incorrect statement is: **Water gas is a mixture of carbon monoxide and water.**

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