Question

what can a drop of liquid mercury be described as?
a pure substance and a compound
an impure substance that is reactive
an impure substance that is unreactive
a pure substance and an element

Explanation:

Mercury is an element on the periodic table. Elements are pure substances as they consist of only one type of atom. A drop of liquid mercury is just mercury in its liquid - state and is not a compound (which has two or more different elements chemically combined). Also, mercury is a pure substance, not an impure one.

Answer:

a pure substance and an element