Question

plastic floats in water and milk ..is it true??

Answer 1

only plastics floats on water and milk gets dissolved in water and form solution.
density is the factor both cases depends on it.

Answer 2

it's totally depends on the density of plastic.
if the density is greater they will sink other wise they will float.
so we can not say that plastic floats in water and milk.
it's a relative term not all the plastics float.