how do you identify a substance (solid, liquid or gas), given the boiling and melting points?
 
 
 
 
 

 

there are three common states of matter: solid, liquid and gas (plasma is the fourth state, but is not so commonly encountered). we can use melting and boiling points to determine if the given substance is solid, liquid or gas, given the ambient temperature. 
the melting point is the temperature at which a substance converts from a solid state to a liquid state. similarly, boiling point is the temperature at which a substance converts from a liquid state to a gas state. 
there can be a few different scenarios:
the ambient temperature is less than the melting point and the boiling point: the substance is a solid.
the ambient temperature is more than the melting point, but is less than the boiling point: the substance is a liquid.
the ambient temperature is more than the melting point and the boiling point: the substance is a gas.
thus, a knowledge of the melting point, the boiling point and the ambient temperature is enough to determine if a given substance is a solid, liquid or gas.
hope this helps.