What is the difference between fixed nitrogen and nitrogen gas. Choices are in the picture.

c. would be the answer : )

explanation:

nucleic acid molecules are incredibly complex, containing the code that guarantees the four different nucleotide units comprise dna, the nucleic acid of interest to the genealogist. and one of four nitrogen-containing molecules called nucleotides

ok yes, but what is the question? as soon as you ask the actual question i will answer it. : )

d. changes in climate and historical records

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