MCQ Detailed View

Air is a mixture of gases that forms the Earth’s atmosphere. It is essential for the survival of living organisms and for many chemical and physical processes. The main constituent of air is nitrogen (N₂), which makes up approximately 78% of the atmosphere by volume.

Oxygen (O₂) is the second major component, comprising about 21% of air, and is essential for respiration in humans, animals, and combustion processes. The remaining 1% consists of gases such as argon (Ar), carbon dioxide (CO₂), neon (Ne), helium (He), and trace amounts of other gases. Water vapor is also present in varying amounts depending on humidity and location.

Nitrogen is an inert gas under most conditions, meaning it does not easily react with other substances. This property helps stabilize the atmosphere and prevents rapid oxidation of materials. Nitrogen also plays a vital role in the nitrogen cycle, which is crucial for converting nitrogen into forms usable by plants and animals.

Understanding the composition of air is a fundamental topic in chemistry, particularly in atmospheric chemistry and gas laws. It explains why certain reactions, like combustion, require oxygen and why the majority of air is not reactive. Nitrogen’s abundance also highlights its use in industrial applications, such as the production of fertilizers, inert gas environments, and chemical manufacturing.

Knowing the main constituent of air is critical for understanding chemical reactions in the atmosphere, environmental science, and basic biology. It also helps students grasp the balance of gases that sustain life on Earth and the role of each component in natural and industrial processes.