Given a scientific passage and an answer, generate a question for the given answer.
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Question: Passage: The biological electron transport chain provides for an orderly, stepwise transfer of electrons. Both NADH (reduced nicotinamide adenine dinucleotide) and FADH2 (reduced flavin adenine dinucleotide) are energyrich molecules that liberate a large amount of energy during oxidation. Free energy released during the transfer of electrons from either of these molecules to oxygen drives the synthesis of ATP (adenosine triphosphate) formed during respiratory metabolism. The reactions are as follows:. Answer: oxidation

Answer: The biological electron transport chain provides for an orderly, stepwise transfer of electrons. both nadh (reduced nicotinamide adenine dinucleotide) and fadh2 (reduced flavin adenine dinucleotide) are energy rich molecules that liberate a large amount of energy during what?

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: The core is the Sun's innermost layer. The core is plasma. It has a temperature of around 15 million degrees Celsius (C). Nuclear fusion reactions create the immense temperature. In these reactions, hydrogen atoms fuse to form helium. This releases vast amounts of energy. The energy moves toward the outer layers of the Sun. Energy from the Sun's core powers most of the solar system. Answer: core

Answer:
The innermost layer of the sun is known as what?