Given a scientific passage and an answer, generate a question for the given answer.

Passage: A single-replacement reaction is one in which an element replaces another element in a compound. An element is in either the solid, liquid, or gas state and is not an ion. The example below shows the reaction of solid magnesium metal with aqueous silver nitrate to form aqueous magnesium nitrate and silver metal. Answer: single-replacement reaction
In this type of reaction, an element replaces another element in a compound, and the element is in any state of matter but is not an ion?

Passage: Monarch butterflies gather in large groups as they migrate 2,500 miles south each fall. They return to the north in the spring. This migration is a cycle that repeats every year. Answer: migration
What do we call the seasonal movement of animals?

Passage: Field lines represent lines of force in the electric field around a charged particle. The lines bend when two particles interact. What would the lines of force look like around two negatively charged particles?. Answer: field lines
What are the lines of force in the electric field around a charged particle called?