A sample of expired air is trapped in a gas jar. A second gas jar contains normal atmospheric air. A lighted candle is put into each gas jar, as illustrated. The time for each flame to extinguish is recorded. While the candles burn, they use the oxygen present in the jar. The table presents the findings from this experiment. Gas jar X: $15\ \text{s}$ Gas jar Y: $9\ \text{s}$ Explain why the results for jars X and Y are different.
- AJar X contains atmospheric air which has more carbon dioxide.
- BJar X contains expired air which has more carbon dioxide.
- CJar Y contains atmospheric air which has less oxygen.
- DJar Y contains expired air which has less oxygen.