Standard Science Primary 5 Systems

Which of the following correctly compares the air we breathe in and the air we breathe out?

A Inhaled air contains more carbon dioxide than exhaled air.
B Exhaled air contains more nitrogen than inhaled air.
C Exhaled air contains more water vapour and carbon dioxide than inhaled air.
D Inhaled air contains less oxygen than exhaled air.
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Worked Solution

Step 1: Body cells use oxygen and produce carbon dioxide and water vapour during respiration. Step [2-9]: These waste products are released into the blood and transported to the lungs. Step [2-9]: Therefore, exhaled air has more CO2 and moisture.

Correct answer: Exhaled air contains more water vapour and carbon dioxide than inhaled air.

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