Iron fillings are added to water, and sink to the bottom. is this a mixture or a solution ?

It is a Mixture

A mixture is a combination of different things that are not chemically bonded.

A solution is a special type of homogeneous mixture composed of two or more substances. A solute is a substance dissolved in another substance, known as a solvent and when this happens a solution is formed

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.

i think   the answer is c hope i'm right