Which part of a tree always grows down because of gravity?

a. the roots
b. the trunk
c. the leaves
d. the branches

precipitation

explanation:

when it goes from cloud to rain/back to earth in the form of rain

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.