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

Q: Passage: Radioactivity is the ability of an atom to emit, or give off, charged particles and energy from the nucleus. The charged particles and energy are called by the general term radiation . Only unstable nuclei emit radiation. When they do, they gain or lose protons. Then the atoms become different elements. (Be careful not to confuse this radiation with electromagnetic radiation, which has to do with the light given off by atoms as they absorb and then emit energy. ). Answer: radioactivity

A: What is the ability of an atom to emit, or give off, charged particles and energy from the nucleus?
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Q: Passage: The wide range of movement allowed by synovial joints produces different types of movements. Angular movements are produced when the angle between the bones of a joint changes. Flexion, or bending, occurs when the angle between the bones decreases. Moving the forearm upward at the elbow is an example of flexion. Extension is the opposite of flexion in that the angle between the bones of a joint increases. Rotational movement is the movement of a bone as it rotates around its own longitudinal axis. Movement of the head as in saying "no" is an example of rotation. Answer: angular

A: What type of movements are produced when the angle between the bones of a joint changes?
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Q: Passage: Pollutants in surface water can filter into the ground and enter a groundwater aquifer. Irrigation water can bring pesticides and other chemicals. Water can seep through landfills. Tanks of gasoline stored underground can leak. Answer: groundwater aquifer

A:
Pollutants in surface water can filter into the ground and enter a what?
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