The compound in which mass percentage of carbon is 75% and that of hydrogen is 25% is

Options

A. `C_(2)H_(6)`
B. `C_(2)H_(2)`
C. `CH_(4)`
D. `C_(2)H_(4)`

Answer

To determine the compound in which the mass percentage of carbon is 75% and that of hydrogen is 25%, we can follow these steps:

### Step 1: Assume a Mass of the Compound
Assume the total mass of the compound to be 100 g. This simplifies the calculations since the percentages can be directly converted to grams.

### Step 2: Calculate the Mass of Carbon
Given that the mass percentage of carbon is 75%, we can calculate the mass of carbon in the compound:
\[ \text{Mass of Carbon} = \frac{75}{100} \times 100 \, \text{g} = 75 \, \text{g} \]

### Step 3: Calculate the Mass of Hydrogen
Similarly, for hydrogen, which has a mass percentage of 25%:
\[ \text{Mass of Hydrogen} = \frac{25}{100} \times 100 \, \text{g} = 25 \, \text{g} \]

### Step 4: Calculate Moles of Carbon
Now, we can calculate the number of moles of carbon. The atomic weight of carbon (C) is approximately 12 g/mol:
\[ \text{Moles of Carbon} = \frac{\text{Mass of Carbon}}{\text{Atomic Weight of Carbon}} = \frac{75 \, \text{g}}{12 \, \text{g/mol}} = 6.25 \, \text{mol} \]

### Step 5: Calculate Moles of Hydrogen
Next, we calculate the number of moles of hydrogen. The atomic weight of hydrogen (H) is approximately 1 g/mol:
\[ \text{Moles of Hydrogen} = \frac{\text{Mass of Hydrogen}}{\text{Atomic Weight of Hydrogen}} = \frac{25 \, \text{g}}{1 \, \text{g/mol}} = 25 \, \text{mol} \]

### Step 6: Determine the Mole Ratio
Now we find the ratio of moles of carbon to moles of hydrogen:
\[ \text{Ratio of Carbon to Hydrogen} = \frac{6.25}{25} = \frac{1}{4} \]

### Step 7: Identify the Compound
The ratio of carbon to hydrogen is 1:4, which corresponds to the molecular formula CH₄ (methane).

### Conclusion
Thus, the compound in which the mass percentage of carbon is 75% and that of hydrogen is 25% is **CH₄**.

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