Soru

A $500\text{ cm}^3$ sample of air collected near an industrial plant containing nitrogen ($\text{N}_2$), oxygen ($\text{O}_2$), carbon dioxide ($\text{CO}_2$), and sulfur dioxide ($\text{SO}_2$) pollutant was passed through concentrated potassium hydroxide ($\text{KOH}$) solution, reducing the gas volume to $485\text{ cm}^3$. The residual gas mixture was subsequently passed through excess alkaline solution of pyrogallol, resulting in a final volume of $383\text{ cm}^3$. What is the percentage by volume of oxygen in the original air sample?