Why is elemental zinc considered a pure substance? Select one:
It is a metal.
It is a mixture of different atoms.
All elements are considered pure substances.
It must be created in a lab.

 C... Because Zinc is made of only one type of atoms.

Explanation: All elements are made of one type of atom. Pure gold is made out of only gold atoms, silver out of only silver atoms, etc.

pure substance: iron,copper

impure substance: water,charcoal

the potential energy of the reactants is 200j.

from the energy diagram, the energy of the product formed is 350j; this means that, this reaction is an endothermic reaction, because it absorbs energy from its environment.