The two substances that scientists use are
carbon-14 and carbon-12
Answer:its a covalent bond
Explanation:
"(1) Human population growth reached 6.8 billion in 2010 and it continues to increase" is what led to the other <span>three, since all of these happen from human activity. </span>
Topography is the answer :)
Like DNA, RNA is made up of nucleotides. There are two differences that distinguish DNA from RNA: (a) RNA contains the sugar ribose, while DNA contains the slightly different sugar deoxyribose (a type of ribose that lacks one oxygen atom), and (b) RNA has the nucleobase uracil while DNA contains thymine.