Urgent!!Breathed air

"Breathed air contains more oxygen than carbondioxide."

The above statement is true.

It is a misconception that the breathed air contains a lot of carbondioxide. Actually, only a smallproportion of oxygen undergoes gas exchange to give carbon dioxide. Averagelyspeaking, breathed air contains 78% of nitrogen, 16% of oxygen, 4% of carbondioxide, saturated water vapour, and a small amount of other gases.

(Averagely speaking, unbreathed ari contains 78% of nitrogen, 21% of oxygen,0.04% of carbon dioxide, a variable amount of water vapour, and a small amountof other gases.)

Breathed air contains more oxygen than carbon dioxide.
It is false!

This is the correct answer:
Breathed air contains less oxygen and more carbon dioxide than unbreathed air.

Addition:
The temperature of breathed is higher than that of unbreathed air.
Breathed air contain more water vapour than unbreathed air.

據講氧氣佔兩成，二氧化碳只有0.04%。

2015-03-08 19:22:57 補充：
你係指exhausted air 嗎？