Because mercury is a metal.
Barometers can use any liquid. A dense liquid that makes for a short column at room temperature, is mercury.
Solid iron will float in liquid mercury. In most liquids it will sink.
When Mercury is at any temp. Over -47 it will stay a liquid
Stones do not float in mercury because mercury is a very dense liquid, much denser than a stone. Any object denser than mercury will sink in it. In general, objects float in a liquid only if they are less dense than the liquid.
Earth is the only known planet to have any sort of liquid on its surface.
mercury is a liquid
scientists say there is but they are not sure.
Which rock? Any liquid that is dense enough will support a rock; the most common would likely be mercury, in which even iron floats.
Liquid Mercury is a liquid with the density 13,534 g/cm3.
Mercury is liquid at room temperature. I don't remember any others.
At room temperature, the element Mercury is a liquid.