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

[EX Q]: 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
[EX A]: 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?

[EX Q]: Passage: The force of gravity is called weight. Near the surface of a planet, it has magnitude and is directed perpendicular to its surface. This is different from the Gravitational Constant, and differs from planet to planet. Answer: weight
[EX A]: What is the force of gravity called?

[EX Q]: Passage: Symbiosis is a close relationship between two species in which at least one species benefits. Answer: symbiosis
[EX A]:
What is a close relationship between two species in which at least one species benefits?