The percentage composition of carbon by mole in methane is:

Options

A. `25%`
B. `80%`
C. `75%`
D. `20%`

Explanation

To find the percentage composition of carbon by mole in methane (CH₄), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Molecular Formula**:
The molecular formula of methane is CH₄. This indicates that there is 1 carbon atom and 4 hydrogen atoms in one molecule of methane.

2. **Determine the Number of Moles**:
In one mole of methane (CH₄), there are:
- 1 mole of carbon (C)
- 4 moles of hydrogen (H)

3. **Calculate the Total Number of Moles**:
The total number of moles in one mole of methane is calculated as:
\[ \text{Total moles} = \text{moles of C} + \text{moles of H} = 1 + 4 = 5 \text{ moles} \]

4. **Find the Mole Fraction of Carbon**:
The mole fraction of carbon in methane is given by:
\[ \text{Mole fraction of C} = \frac{\text{moles of C}}{\text{total moles}} = \frac{1}{5} \]

5. **Calculate the Percentage Composition by Mole**:
To find the percentage composition of carbon by mole, multiply the mole fraction by 100:
\[ \text{Percentage of C} = \left(\frac{1}{5}\right) \times 100 = 20\% \]

### Final Answer:
The percentage composition of carbon by mole in methane is **20%**.

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