How does your second table support the claim that the number of atoms — and therefore mass — is conserved during a chemical reaction?

a compound is a molecule made of atoms from different elements.

a. by the combination of an unlimited number of elements

the correct answer is:

a. formation of precipitation

each chemical family is represented as a group or column on the periodic table. based on chemical properties, there are 6 types of chemical families. group 1 represents alkali metals, group 2 represents alkaline earth metals, groups 3 to 12 represent transition metals, groups 13 to 16 represent non-metals and other metals, group 17 represents halogens and group 18 represents noble gases.