What do we mean when we say a chemical reaction is balanced? (several choices can be correct.)
there is an equal number of solids, liquids, and gases on both sides of the reaction arrow.
there is an equal number of products on the right side of the equation as there are reactants on the left side of the
arrow.
the total number of each atom is the same on both sides of the reaction arrow.
the net charge on both sides of the reaction arrow is the same.

Will give imagine you are given a mystery element. it is, however, a discovered and known element. you may perform a maximum of two observations or tests to determine its identity. time and money is critical, so you need to prioritize your tests. if you can get by with a single test, you get 100 super-geek points from your research lab team. pick your two tests, number them as #1 and #2, and justify why you think these two will certainly be enough (and why the first might well be enough all by itself.) the available tests are classification into metal, non-metal, or metalloid, count of valence electrons, count of electron shells, atomic radius (error range: +/- 1 pm), electronegativity (error range: +/- 0.1), first ionization energy (error range: +/- 10 kj/mole), melting point (error range: +/- 10 c), and boiling point (error range: +/- 20 c).