Milady Esthetics State Board Practice Test

Air is primarily composed of which of the following?

1. Two parts oxygen, three parts nitrogen

2. One part oxygen and four parts nitrogen

3. One part carbon dioxide, five parts nitrogen

4. Three parts oxygen, one part carbon dioxide

The correct answer is: One part oxygen and four parts nitrogen

Air is primarily composed of one part oxygen and four parts nitrogen, which aligns with the correct answer. In the Earth's atmosphere, nitrogen constitutes about 78% of the air, while oxygen makes up about 21%. This ratio is important in understanding respiratory processes, combustion, and various environmental factors. The other options present incorrect ratios or compositions. The first choice suggests an incorrect ratio of oxygen to nitrogen, misrepresenting the dominant components of the atmosphere. The third choice erroneously includes carbon dioxide as a primary component in significant amounts, which does not reflect its actual prevalence in the atmosphere, where it constitutes only about 0.04%. Lastly, the fourth choice incorrectly emphasizes carbon dioxide and has an inaccurate proportion of oxygen. Focusing on the correct composition is fundamental for knowledge in both environmental science and esthetic practices related to air quality and its effects on skin and health.