Worksheet – Life Cycle of Stars 1 (Year 10 Physics) April 29, 2025April 29, 2025 Navu Full Name: Q1: What is the name given to the initial cloud of dust and gas from which stars form? Protostar Nebula Main sequence star Red giant Q2: What is the primary force that pulls dust and gas together to form a protostar? Thermal expansion Nuclear fusion Gravity Electromagnetic force Q3: What element primarily undergoes nuclear fusion in the core of a newly formed star? Helium Carbon Oxygen Hydrogen Q4: What is the stage in a star's life when the outward pressure from thermal expansion balances the inward force of gravity? Protostar stage Red giant stage Main sequence stage White dwarf stage Q5: How long does the main sequence stage typically last for a star like the Sun? A few thousand years Several million years Several billion years A few hundred billion years Q6: When does a star leave the main sequence? When it begins to cool down When the hydrogen in its core begins to run out When it starts fusing heavier elements When it becomes more stable Q7: What causes the outer layers of a star to expand when it becomes a red giant or red supergiant? The cooling of the core. The energy released by the hot core. The decrease in gravitational force. The depletion of helium. Q8: Why does a red giant or red supergiant appear red? Its core temperature increases. Its surface cools down. It emits more red light during fusion. It absorbs all other colors of light. Q9: What is left behind after a small-to-medium-sized star ejects its outer layers? A neutron star A black hole A white dwarf A protostar Q10: What process allows big stars to produce heavier elements after the main sequence? Gravitational collapse Thermal expansion Nuclear fusion Radioactive decay Q11: What is the explosive event that occurs at the end of a big star's life? Planetary nebula formation White dwarf formation Supernova Red giant expansion Q12: What type of core is left behind after a supernova explosion of a massive star? A white dwarf A red giant A neutron star A protostar Q13: Under what condition does a collapsing massive star become a black hole instead of a neutron star? If its initial temperature was too low. If it does not undergo nuclear fusion. If it is massive enough. If it loses too much mass during the supernova. Q14: What is a defining characteristic of a black hole? It emits a large amount of light. It has a very low density. Not even light can escape its gravitational pull. It is primarily composed of hydrogen and helium. Q15: What is the Sun currently classified as? A protostar A red giant A main sequence star A white dwarf Submit