Solution

DNA is a long polymer made from repeating units called nucleotides which do not generally exist as a single molecule but as pairs of molecules held tightly together in double strands in a entwined in a helix model. The nucleotides of DNA has a nitrogenous base, deoxyribose and a phosphate group. The nucleotide is named as per the nitrogenous base and is either a purine or a pyrimidine. The purines are paired with a pyrimidine in a double helix and has 10.5 pairs. hence a single coil of DNA will on an average have 10 purine N2 bases.