Standard Science Primary 5 Systems

Compare the air we breathe in with the air we breathe out. Which of the following is correct?

A Inhaled air contains more carbon dioxide than exhaled air.
B Exhaled air contains more oxygen than inhaled air.
C The amount of nitrogen in exhaled air is much less than in inhaled air.
D Exhaled air contains more water vapour and is warmer than inhaled air.
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Worked Solution

Step 1: Body uses oxygen and produces carbon dioxide/heat/water vapour. Step [2-9]: Exhaled air reflects these changes. Step [2-9]: Thus, exhaled air is warmer and more moist.

Correct answer: Exhaled air contains more water vapour and is warmer than inhaled air.

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