It depends on the type of syrup. Generally, syrup is denser than water and will sink in it. However, some syrups, such as maple syrup, have a lower density and may float on top of water.
until you mix it
rubber
Aluminum powder will sink in water because it is denser than water.
Depends on what they're dropped into. Water - no. But drop them into something that's denser than aluminium and they will float.
oil
Shape the aluminum to look like a boat, so it displaces enough water to float. The force supporting the aluminum is the buoyant force. It is equal to the weight of the volume of water displaced.
Sink
A feather is light enough to float in syrup but not in water due to differences in their densities and viscosities. The thicker consistency of the syrup provides more buoyant force to support the feather compared to water.
Yes
the air inside the can keeps it afloat
Aluminum.