By definition a rock is in a solid state.
no, it does not exist
Yes, there are some substances like carbon dioxide and ammonia that can exist as a liquid, gas, and solid at different temperatures and pressures. These substances undergo changes in state based on variations in temperature and pressure.
The water has already reached the 212 degree boiling point. At 212 degrees the water can exist as either a liquid or a vapor. Absorbing the latent heat pushes liquid to the vapor state without any change in temperature.
A liquid state will fit into a container of any shape and size, as it takes the shape of its container.
Any gas, liquid or solid can exist in all states of matter.
Any chemical difference exist.
There is no solvent in magma. Rocks turn to a liquid state because of super-heating, not because the solids were dissolved in any solvent.
Rocks are made of minerals. When rocks melt, the minerals become fluid or in a liquid state. Also, when a mineral turns to a liquid it no longer meets the expectaions required for it to be called a mineral.
Which rock? Any liquid that is dense enough will support a rock; the most common would likely be mercury, in which even iron floats.
Matter can exist in four forms: plasma, gas, liquid, solid.
Carbon dioxide, for example, can exist in a solid state (commonly known as "dry ice") and if heated, it turns into a gas, without going through the liquid state. However, that does not mean that carbon dioxide cannot form a liquid under any circumstances. For every chemical, there is what chemists call a "phase diagram" which shows the different phases (solid, liquid, and gas) which exist under different combinations of temperature and pressure (pressure normally refers to air pressure, although other kinds are possible). Almost any chemical is capable of forming any phase under the right combination of temperature and pressure. The only exception is helium, which has no solid phase. It can be a gas or a (very cold) liquid, but not a solid. That is because helium is the most inert of all inert elements, and it has extremely little inter-atomic attraction, which is insufficient to form a solid phase even at the coldest possible temperature (absolute zero, in degrees Kelvin). The assertion in your question that some substance cannot exist in both the liquid and gaseous state is not true. Any substance, if heated sufficiently, will become a gas. Some substances require higher temperatures than others, of course.
None of the above. Mad can be used to describe either anger or insanity, both of which are abstract concepts that do not exist in any physical state.
no, it does not exist
as a gas, solid or liquid
Gas, Solid, & Liquid.
Under normal conditions - the ones we are accustomed to - it is a gas.
Solid, liquid, gas, or plasma. A substance can occur in any one these states. All matter occurs in one of these 4 states. These are the 4 states of matter.