What statement about nitrogen is consistent with its chemistry? (1) It makes up \(78 \%\) of the earth's atmosphere by volme (2) It is a colourless, odourless, tasteless gas. (3) It readily reacts with hydrogen to form \(\mathrm{NH}_{3}\) that is used in fertilizers (4) It is the most volatile component of liquid air with a boiling point of \(-196^{\circ} \mathrm{C}\). (a) \(1,2,3\) (b) \(2,33,4\) (c) \(1,2,4\) (d) \(1,3,4\)

Understanding the chemical composition of Earth's atmosphere is fundamental to appreciating the role of nitrogen in our air. Earth's atmosphere is a complex mixture of various gases, each with its unique role and properties. Nitrogen gas (N₂) is the most abundant, making up about 78% of the atmosphere by volume. This is followed by oxygen, which accounts for approximately 21%, and other gases like argon, carbon dioxide, and trace gases all together make up the remaining 1%.

This composition has significant implications for life on Earth, climate processes, and even industrial applications. Nitrogen itself, despite its abundance, is relatively unreactive in its diatomic form, which is why it plays a crucial role as a diluent for oxygen, preventing fires from becoming too easily ignited.

Nitrogen gas (N₂) possesses several physical properties that affect both the environment and its industrial uses. It is a colorless, odorless, and tasteless gas. These properties make it difficult to detect without the use of specialized equipment. Nitrogen's lack of color and smell contributes to the clarity and freshness of the earth's atmosphere.

Being chemically inert due to the strong triple bond holding its two atoms together, nitrogen does not easily participate in reactions at ambient temperatures. However, it is essential for life - plants need it to form proteins, and it is a crucial component of genetic material like DNA and RNA. Industrial processes can convert nitrogen gas into more reactive compounds, which are useful for different applications including the production of fertilizers.

One of the most significant industrial methods for fixing nitrogen is the Haber process. This chemical reaction synthesizes ammonia (NH₃) from nitrogen gas (N₂) and hydrogen gas (H₂) using a metal catalyst at high temperatures and pressures. The reaction can be represented by the following equation: N₂(g) + 3H₂(g) ⇌ 2NH₃(g).

The Haber process is critical for producing ammonia, which is a key ingredient in fertilizers, and therefore has a substantial role in global agriculture. The ability to mass-produce ammonia from nitrogen in the air has allowed for much higher yields in food production, supporting global population growth.

Nitrogen, due to its physical properties, has a low boiling point at -196°C (-321°F). This makes it the most volatile component of liquid air, signifying that it will boil and convert from liquid to gas at lower temperatures compared to other gases in the atmosphere. In terms of industrial applications, this property of nitrogen is utilized in cryogenics where extreme cold is required, for preserving biological specimens, and in the production of liquid nitrogen for various uses.

The low boiling point also means that nitrogen remains a gas across a wide range of temperatures on Earth's surface, supporting its role as a major part of the atmosphere.