NaSO4 is added to 0.986 L of water to create 0.100 mol/L SO4-2 solution. What is the percent by mass of NaSO4 in the solution?

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 answer to your question is c

geosphere and hydrosphere.

this is because the geosphere has to do with geological events, while the hydrosphere controls all water on earth.