1. The most reactive metal is Francium (Fr). This is because it has the lowest ionization energy and the highest electronegativity among all the elements in the periodic table. However, Francium is a very rare and unstable element, so it is not commonly used in chemical reactions.
2. The metals can be ranked in order of increasing reactivity as follows: Gold (Au), Silver (Ag), Copper (Cu), Mercury (Hg), Lead (Pb), Tin (Sn), Iron (Fe), Zinc (Zn), Aluminum (Al), Magnesium (Mg), Sodium (Na), Potassium (K), Calcium (Ca).
3. The chemical equations for each single replacement reaction that took place are:
a. Zinc (Zn) + Copper (II) sulfate (CuSO4) → Zinc sulfate (ZnSO4) + Copper (Cu)
b. Iron (Fe) + Copper (II) sulfate (CuSO4) → Iron (II) sulfate (FeSO4) + Copper (Cu)
c. Aluminum (Al) + Copper (II) sulfate (CuSO4) → Aluminum sulfate (Al2(SO4)3) + Copper (Cu)
4. Yes, Fe^3+ was reduced to Fe^2+. The reducing agents were Zinc (Zn), Iron (Fe), and Aluminum (Al) which all have a higher reactivity than Fe.