Sodium-24 has a half-life of 15 hours. What mass in grams of Na-24 will remain in an 18.0 g sample after 90 hours? Give your answer to two significant digits. grams?

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.

the correct answer to this question is 2