The systematic name of which compound is nitrogen trihydride that is widely used in many industrial processes, and as a fertiliser and refrigerant?

Ammonia

The correct answer is option 4. Ammonia.

Ammonia, with the chemical formula \(NH_3\), is an inorganic compound composed of one nitrogen atom bonded to three hydrogen atoms. It is commonly referred to as nitrogen trihydride due to its composition.

Ammonia is widely used in various industrial processes. It is a key component in the production of fertilizers, such as ammonium nitrate and urea, which are essential for agricultural practices to enhance soil fertility and crop yields. Additionally, ammonia is used in the manufacture of various chemicals, including ammonium sulfate, ammonium phosphate, and other nitrogen-containing compounds used in pharmaceuticals, cleaning products, and explosives.

Ammonia has also been used as a refrigerant in refrigeration systems, particularly in industrial and commercial applications. It has favorable thermodynamic properties for refrigeration, such as a high latent heat of vaporization, making it efficient for cooling purposes. However, due to safety concerns related to its toxicity and flammability, the use of ammonia as a refrigerant has decreased in favor of other refrigerants in some applications.

Ammonia is a colorless gas with a pungent odor. It is highly soluble in water, forming a strongly alkaline solution known as ammonium hydroxide. Ammonia is lighter than air and can be easily liquefied under pressure, making it convenient for storage and transportation.

As a fertilizer, ammonia provides a readily available source of nitrogen, which is essential for plant growth and development. It can be applied directly to soil or used as a precursor for the synthesis of other nitrogen-containing fertilizers.

In summary, ammonia \((NH_3)\) is the compound commonly known as nitrogen trihydride. It is utilized in various industrial processes, as a fertilizer to enhance soil fertility, and as a refrigerant for cooling applications due to its favorable thermodynamic properties.