Where is the bottle? There are droplets so it is not empty
because it can there is no right or wrong answer
Because there's never any change in it.
Yes it is. Everything in the empty set (which is nothing of course) is also in the empty set. If it's not in the empty set, it's not in the empty set. The empty set has no proper subsets, though, or...
Simple Answer is, You cant. Once you empty the trash you can "un-empty it"