Antoine lavoisier found that mass was conserved in chemical reactions when he saw that a) heat was released in chemical reactions. b) the products differed greatly from the reactants. c) the mass of the products was the same as that of the reactants. d) the mass of the products were heavier than the mass of the reactants.

C is the answer. Mass stays the same.

The activity series is shown in the attached picture. if the element is below the other, then you can displace the other. following the activity series as a guide, the reactions are as follows: nickel and aluminum chloride3 ni + 2 alcl₃  → 3 nicl₂ + 2 albarium and copper bromideba + cubr  →  no reaction because cu is less oxidizable than bapotassium nitrate and aluminum3 kno₃ + al  → al(no₃)₃ + 3 ksodium phosphate and zincnaso₄ + zn  → znso₄ + na