Question: what is the chemical difference between uracil and thymine?
Answer: Key Differences Between Thymine and Uracil Methyl group is absent in uracil whereas present in thymine at the C-5 position. The molecular formula of thymine is C5H6N2O2, whereas the molecular formula of uracil is C4H4N2O2. Thymine has a molar mass of 126.1133 g/mol and uracil has a molar mass of 112.0868 g/mol.