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

Input: Consider Input: Passage: A lens that causes the light rays to bend away from its axis is called a diverging lens. Ray tracing is the technique of graphically determining the paths that light rays take. The image in which light rays from one point on the object actually cross at the location of the image and can be projected onto a screen, a piece of film, or the retina of an eye is called a real image. Thin lens equations are. Answer: diverging lens

Output: What do you call a lens that causes the light rays to bend away from its axis?

Input: Consider Input: Passage: Hydrogen is a very reactive gas, and the alkali metals are even more reactive. In fact, they are the most reactive metals and, along with the elements in group 17, are the most reactive of all elements. The reactivity of alkali metals increases from the top to the bottom of the group, so lithium (Li) is the least reactive alkali metal and francium (Fr) is the most reactive. Because alkali metals are so reactive, they are found in nature only in combination with other elements. They often combine with group 17 elements, which are very "eager" to gain an electron. At the URL below, you can watch a video that shows just how reactive the alkali metals are. Answer: combination

Output: Because alkali metals are so reactive, they are found in nature only in ________ with other elements?

Input: Consider Input: Passage: That may depend on the plant. Start with moss. The typical nonvascular plant. But such a simple plant has a very interesting life cycle. Whereas most kinds of plants have two sets of chromosomes in their vegetative cells, mosses have only a single set of chromosomes. So, how does meiosis occur?. Answer: single set
Output: How many set of chromosomes do moss have?