What type of bond allows heat and electricity to move freely throughout the material?

That would be an ionic bond since it has electrons to spare, rather than a convalent bond where all the electrons are taken up thus it is not a good conductor

c is the answer because when something is left after something evaporates that shows the chemical change.

we can conclude that the melting point of table salt is above room temperature (it's actually 801 deg c). the melting point of mercury must be below room temperature (- 39 deg c).