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

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

Question: Passage: Not all wetlands are alike, as you can see from Figure below . Wetlands vary in how wet they are and how much of the year they are soaked. Wetlands also vary in the kinds of plants that live in them. This depends mostly on the climate where the wetland is found. Types of wetlands include marshes, swamps, and bogs. Answer: wetlands

Answer: Marshes, swamps, and bogs are types of what?

Question: Passage: Core electrons are the electrons that are closer to the nucleus and therefore do not participate in bonding. Answer: bonding

Answer:
Because core electrons are closer to the nucleus, they are not involved in what?