7. DNA is essential to living organisms because it O is a spiral helix can prevent disease O carries the genetic code O can break apart

DNA is essential...because it carries the genetic code.

Explanation:

Although the other statements are true about DNA, it's a spiral helix and can break apart, its main function is that it contains the genetic code for organisms.

the number of valence electrons for each molecule or ion is shown beneath the structure. remember hydrogen will not have more than two electrons. this hydrogen is part of a covalent bond (sharing two electrons). a double bond here would cause hydrogen to share four electrons with phosphorus.