Question

If a combustion, 4 kg of organic compound gives 11 kg of CO$_2$, the percentage of carbon in the compound will be _________

• A. 50
• B. 75
• C. 25
• D. 60

Hint:

Use the ratio $\frac{12}{44}$ to extract the mass of carbon from the mass of CO$_2$. Then compare with the original compound to find the percentage.

Answer 1

The Correct Option is B

From the question, we know:
- Mass of organic compound = 4 kg
- Mass of CO$_2$ produced = 11 kg
We need to find the amount of carbon that was present in the original compound.
Step 1: Determine the mass of carbon in CO$_2$
Molecular mass of CO$_2$ = 44 g/mol (12 for C and 32 for O$_2$)
Mass of carbon in one mole of CO$_2$ = 12 g
So, the fraction of carbon in CO$_2$ is:
\[ \frac{12}{44} \]
Step 2: Calculate the mass of carbon in 11 kg (or 11000 g) of CO$_2$
\[ \text{Mass of carbon} = \frac{12}{44} \times 11000 = 3000\ \text{g} = 3\ \text{kg} \]
Step 3: Calculate the percentage of carbon in the 4 kg organic compound
\[ \text{Percentage of carbon} = \left( \frac{3}{4} \right) \times 100 = 75% \]