Given a scientific passage and an answer, generate a question for the given answer.
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Question: Passage: Natural gas is delivered to homes, where it is used for cooking and heating. Natural gas is also a major energy source for powering turbines to make electricity. Natural gas releases most of its energy as heat when it burns. The power plant is able to use this heat, either in the form of hot gases or steam, to spin turbines. The spinning turbines turn generators, and the generators create electricity. Answer: natural gas

Answer: What type of gas is delivered to homes to use for cooking and heating?

Question: Passage: Each kind of pigment absorbs specific wavelengths (colors) of light (dashed lines). Sunlight contains many different wavelengths, which you see when they separate into a rainbow. Not all colors of light are used in photosynthesis (solid line). Most plants, algae, and photosynthetic bacteria appear green because they reflect green wavelengths. Their pigments have absorbed the violet-blue and red wavelengths. The amount of photosynthesis depends on the wavelength of light available. Beta-carotene is another type of pigment that absorbs sunlight. Answer: rainbow

Answer: Sunlight contains many different wavelengths, which you see when they separate into what?

Question: Passage: Many common electric devices contain electromagnets. Some examples include hair dryers, fans, CD players, telephones, and doorbells. Most electric devices that have moving parts contain electric motors. You can read below how doorbells and electric motors use electromagnets. Answer: electric motors

Answer:
What type of motor is used in most household devices with moving parts?