Answer
a. element
b. compounds
c. mixture
Work Step by Step
a. Carbon in pencil lead is pure carbon, which is an element.
b. A compound is a mixture of two or more elements. As carbon monoxide contains both carbon and oxygen elements, it is a compound.
c. Mixtures are made up of two or more different substances which are then combined. Orange juice contains the remains of oranges, sometimes pulp, added vitamins/minerals, etc, so it is a mixture.
