On complete combustion $$0.30$$ g of an organic compound gave $$0.20$$ g of carbon dioxide and $$0.10$$ g of water. The percentage of carbon in the given organic compound is ______ (Nearest Integer)

We need to find the percentage of carbon in an organic compound given that 0.30 g of the compound gives 0.20 g of $$CO_2$$ and 0.10 g of $$H_2O$$ on complete combustion.

Find the mass of carbon from $$CO_2$$

Molar mass of $$CO_2$$ = 12 + 2(16) = 44 g/mol

In $$CO_2$$, the mass of carbon = $$\frac{12}{44}$$ of the mass of $$CO_2$$

Mass of carbon = $$\frac{12}{44} \times 0.20$$ g

$$= \frac{2.4}{44}$$ g

$$= 0.05454$$ g

Calculate the percentage of carbon

Percentage of carbon = $$\frac{\text{Mass of carbon}}{\text{Mass of compound}} \times 100$$

$$= \frac{0.05454}{0.30} \times 100$$

$$= 18.18\%$$

Round to nearest integer

$$\approx 18\%$$

The correct answer is 18.