1.Is it logically possible for a solid iron bar to float on water?
Of course it is.
There is no contradiction at all in it.
It is a law of physics that objects with a greater specific gravity than water
(i.e., weighing more than an equal volume of water)
do not float on water
(with certain exceptions such as the phenomenon of "surface tension").
There is no logical necessity about this-that is to say,
it is logically possible for it to be otherwise.
You can even imagine it now
(remember, if you can really imagine it, it is logically possible, but if you can't, it may only mean that your powers of imagination are limited):
you take a piece of iron
(a chemist has verified that it really is iron),
you weigh it, then you plunge it into a vessel of water, and behold, it floats. You have also verified that it is a solid iron bar, not hollow with large air-filled spaces like a battleship; indeed, you have weighed it and measured it so as to make sure that its weight is really greater than that of an equal volume of water. This is a logically possible state-of-affairs, it does not actually occur, but there is nothing logically impossible about it