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

Q: Passage: Electrons are always added to the lowest energy level first until it has the maximum number of electrons possible, and then electrons are added to the next higher energy level until that level is full, and so on. The maximum number of electrons at a given energy level depends on its number of orbitals. There are at most two electrons per orbital. Answer: the lowest

A: Electrons are always added to which energy level first?
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Q: Passage: Photosynthetic organisms include plants, algae, and some bacteria. Answer: photosynthetic

A: Plants, algae and bacteria are all examples of what type of organism?
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Q: Passage: Solids can be categorized by the forces holding the individual atoms, ions, or molecules together. The Table below summarizes the properties of different solids:. Answer: solids

A:
What is categorized by the forces holding the individual atoms, ions, or molecules together?
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