Me pls someone give me the answers to the self-check! 1-5

3 and 5 do not make sense, but I can answer the rest.

1. Reactants are on the left side, and the products are on the right side. Reactants, hence the name, react to form products. So the Cd(NO3)2 compound and the H2S compound are reactants, and the ones on the other side are products.

2. The little letters in parentheses tell you the state of matter. (s) is solid, (aq) is aqueous, (l) is liquid, and (g) is gas.

4. The law of conservation of mass is important, because in reactions mass never disappears just like energy. Mass is never created or destroyed. Mass does not randomly appear, and if the products have less mass than the reactants, it is not that the mass was destroyed.  

answer: atomic mass was originally used to arrange elements on the periodic table, but is no longer used to organize the modern version.

explanation:

originally atomic mass was used to arrange elements on the periodic table from left to right in a row. each column then shows similar properties of elements of a group.

in modern periodic table, the atoms are arranged in increasing atomic number. as atomic number represents the number of protons in an atom which is unique for every atom.