What is the role of electrons in a covalent bond

What is a codon and where is it found

Most of the fossils found in virginia are in the coastal plain, valley, ridge, and appalachian plateau regions, best suggesting that these geographic provinces a) were once covered by seawater. b) are the oldest parts of virginia. c) have a great deal of karst topography. d) have large amounts of sedimentary rock.

Which element forms the basis of all organic organisms a carbon b oxygen c hydrogen d nitrogen