Compare the density of the rubber to water. If it is less that 1 g/mL then it floats in the water.
You must compare density in the same units. So convert to g/mL

The rubber does not float in water.
Alfred Wegener came up with the idea
Answer:
reaction 1 and reaction 4 both are decomposition reactions
while reaction 2 is double displacement reaction and reaction 3 and 5 are combination reactions