the half-life of i-124 is 4.2 days. how long will it take for the mass of i-124 to drop from 10.0 mg to 3.50 mg?

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.

elements make up everything, and they combine to make compounds.

the answer is c