Use the information gathered in the nucleotides molecular structure tutorial to answer the question. select the phrases that accurately describe properties of the most common form of the dna double helix. the nitrogenous bases are exposed to the solvent, whereas the sugar–phosphate backbone of each nucleotide strand is in the interior of the double helix. the phosphodiester bonds between nucleotide residues run in opposite directions in the two strands. base pairs have a spacing of 20 å. dna contains equal amounts of adenine and thymine, and equal amounts of cytosine and guanine. a helical turn consists of about 10 base pairs.