Suppose you are testing the buoyancy of different objects . study the table and choose object with the greatest buoyant force

The formula to calculate buoyant force (FB) states that the upward force exerted on an immersed object is equal to the density (ρ ) of the fluid multiplied by both the fluid’s displaced volume (V) and the gravitational acceleration (g), or
FB = ρ x V x g. 
I hope that helped with what you're doing. 
You can also try water displacement in a graduated cylinder.

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