It is said that only water can assume three forms, solid, liquid, and vapor. Is this true? What about Mercury?

Thanks for your help!It is said that only water can assume three forms, solid, liquid, and vapor. Is this true? What about Mercury?
The original statement is far from true. There are many things that can exist in all three states at various conditions of temperature and pressure.It is said that only water can assume three forms, solid, liquid, and vapor. Is this true? What about Mercury?
Pretty much all elements and compounds have solid liquid and vapor states. these can be displayed in a phase diagram where temperature and pressure are on the x and y axis and different regions correspond to different phases.





For instance, if you saw the phase diagram for water,there is a line crossing at T=100C and P=1atm, this corresponds to the boiling point of water.





The line represents the temperature at which water will boil at different temperatures and pressures.





There is also a line showing where water will freeze and one where gas goes to solid (known as subliming).