Unless it hit you, nothing.
The electricity wouldn't bother you, but; that's a heavy object - if it should hit you, and the acid in the battery is quite strong - if it splashed on you.
I've never tried that, but I am pretty sure the battery would no longer work.
Nothing. you'd get wet, and the battery would get wet, but noting else unless it was plugged in to something, then you may get shocked.
It would get wet and sink!
We would not have a nice pool to Swim in
it would get dirty
once
It will rise of course. The metal that is thrown overboard has mass, and displacement.
If the water were totally Acidic, that is, ph of 0, the it would be as strong as battery acid. Your skin and eyes would burn very badly, and metallic parts of the filter system would become corroded. Normal ph in the 7.0 range is ideal and considered neutral.
It would tip over but still float.
You would get sick and may die but ONLY IF you drank it out of the bottle, not in a pool.
Pool of Radiance happened in 1988.