A compound containing 80% C and 20% H is likely to be:
`C_6 H_6`
`C_2 H_6`
`C_2 H_4`
`C_2 H_2`

Options

A. `C_6 H_6`
B. `C_2 H_6`
C. `C_2 H_4`
D. `C_2 H_2`

Explanation

To determine which compound contains 80% carbon and 20% hydrogen, we can follow these steps:

### Step 1: Calculate the number of moles of Carbon and Hydrogen
- Given percentages:
- Carbon (C) = 80%
- Hydrogen (H) = 20%

- Use the atomic masses:
- Atomic mass of Carbon (C) = 12 g/mol
- Atomic mass of Hydrogen (H) = 1 g/mol

- Calculate moles of Carbon:
\[ \text{Moles of C} = \frac{80 \text{ g}}{12 \text{ g/mol}} \approx 6.67 \text{ moles} \]

- Calculate moles of Hydrogen:
\[ \text{Moles of H} = \frac{20 \text{ g}}{1 \text{ g/mol}} = 20 \text{ moles} \]

### Step 2: Determine the mole ratio of Carbon to Hydrogen
- The mole ratio of C to H is:
\[ \text{C:H} = 6.67 : 20 \]

### Step 3: Simplify the mole ratio
- To simplify the ratio, divide both numbers by the smaller number of moles (6.67):
\[ \text{C:H} = \frac{6.67}{6.67} : \frac{20}{6.67} \approx 1 : 3 \]

### Step 4: Write the empirical formula
- The empirical formula based on the ratio is:
\[ \text{Empirical Formula} = \text{CH}_3 \]

### Step 5: Determine the molecular formula
- To find the molecular formula, we need to determine the value of \( n \) where:
\[ \text{Molecular Formula} = n \times \text{Empirical Formula} \]

- The empirical formula mass of CH3:
\[ \text{Mass of CH}_3 = 12 + (3 \times 1) = 15 \text{ g/mol} \]

- Since we have the empirical formula, we can check the options provided for the molecular formula:
- C6H6 = 78 g/mol
- C2H6 = 30 g/mol
- C2H4 = 28 g/mol
- C2H2 = 26 g/mol

- The molecular formula must be a multiple of the empirical formula. The only option that matches the ratio of 1:3 (C:H) and is a multiple of CH3 is:
\[ \text{C}_2\text{H}_6 \]

### Conclusion
The compound containing 80% Carbon and 20% Hydrogen is likely to be **C2H6**.

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