Organic compound $+{\mathrm{O}}_2⟶ {\mathrm{CO}}_2\left(\mathrm{g}\right) + {\mathrm{H}}_2\mathrm{O}$                                                       

                                         $0.7938$ gram       $0.4428$ gram

Weight of the organic compound=$0.492$ gram

Number of moles of ${\mathrm{CO}}_2$=Number of moles of $\mathrm{C}$

$$\begin{gathered} =\frac{0.7938}{44} \\ \mathrm{Weight} \mathrm{of} \mathrm{carbon}=\left[\frac{0.7938}{44}\right]12=0.216\mathrm{g} \end{gathered}$$

$\mathrm{Weight} \mathrm{of} \mathrm{hydrogen}=\left[\frac{0.4428}{18}\right]2=0.0491$g

$\mathrm{Weight} \mathrm{of} \mathrm{oxygen}=\left[0.492-0.216-0.0491\right]=0.2269\mathrm{g}$

$\%$ of $\mathrm{O}=\frac{0.2249}{0.492}\times 100=46.11\approx 46$