Question 3

Nitrogen is the most abundant gas in Earth's atmosphere.

Nitrogen makes up approximately 78% of Earth's atmosphere, making it the most prevalent gas present. Its abundance plays a crucial role in various biological and chemical processes on our planet.

A) Hydrogen

Hydrogen is not the most abundant gas in Earth's atmosphere; it constitutes only about 0.00005% of the atmosphere. While it is the most abundant element in the universe, its presence in Earth's atmosphere is minimal due to its lightness and tendency to escape into space.

B) Nitrogen

Nitrogen is the correct answer as it constitutes the largest portion of Earth's atmosphere at around 78%. It serves essential functions, including acting as a buffer gas for oxygen and playing a vital role in the nitrogen cycle, which is crucial for life.

C) Helium

Helium is a trace gas in Earth's atmosphere, making up only about 0.0005%. Although it is the second lightest element and is used in various applications, its concentration in the atmosphere is significantly lower than that of nitrogen.

D) Methane

Methane accounts for only about 0.0002% of Earth's atmosphere. While it is an important greenhouse gas, its concentration is much lower compared to nitrogen, making it an incorrect choice for the most abundant atmospheric gas.

Conclusion

Nitrogen's prevalence as the most abundant gas in Earth's atmosphere is well established, comprising a significant majority of the atmospheric composition. In contrast, hydrogen, helium, and methane have much lower concentrations and do not play a comparable role in the atmosphere's overall structure and function.