Marsh gas mainly contains:

Options

A. (a) CO
B. (b) `H_(2)S`
C. (c) `C_(2)H_(2)`
D. (d) `CH_(4)`

Explanation

To solve the question "Marsh gas mainly contains:", we will follow these steps:

### Step 1: Understand what marsh gas is
Marsh gas is a type of gas that is found in marshy areas. It is produced through the decomposition of organic matter, specifically vegetable matter, by anaerobic bacteria.

**Hint**: Think about the environments where marsh gas is typically found and how it is formed.

### Step 2: Identify the process of formation
Marsh gas is formed through anaerobic bacterial decomposition, which means it occurs in the absence of oxygen. This process breaks down organic materials and produces various gases.

**Hint**: Recall the role of bacteria in breaking down organic matter and the conditions required for this process.

### Step 3: Determine the composition of marsh gas
The main components of marsh gas include:
- Methane (CH₄)
- Hydrogen sulfide (H₂S)
- Carbon monoxide (CO)
- Carbon dioxide (CO₂)

However, methane is the most significant component.

**Hint**: Focus on the gases produced during the decomposition process and their relative quantities.

### Step 4: Identify the main component
Methane is the primary component of marsh gas, making up about 50% to 80% of its composition. This high concentration is why methane is often referred to as marsh gas.

**Hint**: Consider which gas is the most abundant in the composition of marsh gas.

### Conclusion
The main component of marsh gas is **methane**.

**Final Answer**: Methane

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