Answer the following question given this paragraph: Stars shine because of nuclear fusion. Fusion reactions in the Sun's core keep our nearest star burning. Stars are made mostly of hydrogen and helium. Both are very lightweight gases. A star contains so much hydrogen and helium that the weight of these gases is enormous. The pressure at the center of a star is great enough to heat the gases. This causes nuclear fusion reactions. Q: What process, which results because of great pressure at the center of a star, causes stars to shine? Choices: - gravitational pull - electric fusion - energy fusion - nuclear fusion A:
nuclear fusion
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Answer the following question given this paragraph: The image focused by the eye travels through the optic nerve to the brain as electrical signals. The brain interprets the signals and "tells" us what we are seeing. Q: How does the image focused by the eye travel to the brain? Choices: - the sensory nerve - the modulated nerve - the secondary nerve - the optic nerve A:
the optic nerve
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Answer the following question given this paragraph: Both conduction and convection transfer energy through matter. Radiation is the only way of transferring energy that doesn't require matter. Radiation is the transfer of energy by waves that can travel through empty space. When the waves reach objects, they transfer energy to the objects, causing them to warm up. This is how the sun's energy reaches Earth and heats its surface (see Figure below ). Radiation is also how thermal energy from a campfire warms people nearby. You might be surprised to learn that all objects radiate thermal energy, including people. In fact, when a room is full of people, it may feel noticeably warmer because of all the thermal energy the people radiate! To learn more about thermal radiation, watch "Radiation" at the URL below. Q: What is the only way of transferring energy that doesn't require matter? Choices: - mutation - evaporation - convection - radiation A:
radiation
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Answer the following question given this paragraph: During a nuclear decay process that occurs by positron emission, a proton is converted into a neutron and a positron. The neutron remains in the nucleus, and the positron is expelled. Overall, the atomic number of the parent nucleus increases by one, and the mass number is unchanged. For example, carbon-11 emits a positron to become boron-11:. Q: What happens to the mass number during a nuclear decay process by positron emission? Choices: - it rises - it decreases - it increases - remains unchanged A:
remains unchanged
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