Question

Mercury is pure or impure substance

Answer 1

Pure mercury contains nothing else but mercury; it is an element, one of the chemical building blocks from which chemical compounds and mixtures are assembled. All the mercuryatoms in it are the same, with atomic number 80. It also happens to be a metal, like gold or silver, whose purity can be 
measured

Answer 2

Mercury is a pure substance and I think I have no need to explain it as u have just asked pure or impure substance. So, I HOPE IT HELPS
;-)