Now, using your Periodic Table tool as a reference, type the symbols for the known elements into their appropriate groups and periods in the modified table below. Note that we’re using the international group numbers (1-18), followed by the American scheme for the A-group elements in parentheses.

explanation:

since this is put under health, i would define "ethical (medical) behavior" the way the oath for doctors is recited.   "first do no harm."

but the term in general means when given a choice between right and wrong, we should always choose right. if we do, then we are practicing ethical behavior.

the law of conservation of mass states that in a chemical reaction, the total mass of reactants is equal to the total mass of products. because atoms are only rearranged in a chemical reaction, there must be the same number of sodium atoms and chlorine atoms in both the reactants and products

i think the answer is terrae but not 100 percent sure. ▓▬▬ §