instruction:
Given a scientific passage and an answer, generate a question for the given answer.
question:
Passage: As we studied in our chapter on the periodic table, we saw that elements share a number of important properties with other elements found in the same group. The chemical behavior of a given element is largely dictated by the configuration of its valence electrons. Many elements have a tendency to gain or lose electrons in order to achieve a more stable configuration. When a neutral atom gains or loses electrons, it becomes an ion. In this lesson, we will look at ways to predict what type of ion a given element is likely to form. Answer: it becomes an ion
answer:
What happens when a neutral atom gains or loses electrons?

question:
Passage: boundary between air masses that is stalled in one place. Answer: aids
answer:
Opportunistic diseases are usually the direct cause of death of people with what disease?

question:
Passage: In the predator-prey example, one factor limits the growth of the other factor. As the prey population decreases, the predator population begins to decrease as well. The prey population is a limiting factor. A limiting factor limits the growth or development of an organism, population, or process. Answer: limiting factor
answer:
What limits the growth or development of an organism, population, or process?