Answer:
Nitrogen thet cannot be used by organisms. C.
Explanation:
Free nitrogen is simply molecular nitrogen (N2). Nitrogen, in its molecular form, consists of two nitrogen atoms bound together with a tripple bond. Because it is very stable, N2 is typically nonreactive, and takes a lot of energy to break them apart. Among these are the amino acids necessary for life to begin and which are the building blocks DNA is made from. Basically, any nitrogen that is in an organic compound is considered “fixed” nitrogen and N2 is considered to be “free” nitrogen
Here, we are required to identify what free nitrogen is.
Molecular nitrogen (N2) in its molecular form, consisting of two nitrogen atoms bound together with a tripple bond as a result of its 5 electrons valency is simply reffered to as Free nitrogen.
Due to its stability, N2 is quite unreactive, and takes a lot of energy (high bond dissociation energy) to break atoms which form the Nitrogen molecules apart.
A number of plants, including beans and other legumes have growths (knobby) on their roots called rhizomes that are capable of “fixing” nitrogen, or break up the nitrogen molecules so that the reactive N atoms to react with organic chemicals to form nitrogen containing organic compounds. Among these are the amino acids necessary for life to begin and which are the building blocks from which DNA is made.
Consequently, nitrogen is only referred to as fixed if it exists in an organic compound, otherwise it is considered to be free nitrogen(N2).
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