In this task, you are given a question and an answer, you would be asked to create the sentence based on the Question-Answer provided. It should be contained within the Question-Answer provided.

Question: What is the term for liquid waste formed by kidneys? Answer: urine
Urine is the term for liquid waste formed by kidneys.

Question: What is one problem with current methods of aluminum production? Answer: environmental contaminants
Environmental contaminants is one problem with current methods of aluminum production.

Question: What is the representative particle in pure metals? Answer: the atom

The atom is the representative particle in pure metals.