elements in carbon family have four valence electrons
molecular_hydrogen is gas. carbon_based_dna has not four_base_pairs valence_electron is electron. carbon_based_dna has four_base_pairs one_of_chemical_elements is carbon. valence_electron is not electron. valencene is chemical_compound. one_of_chemical_elements is hydrogen. one_of_chemical_elements is not carbon. one_of_chemical_elements is not hydrogen.