According to the Hertzsprung-Russell diagram, where are hot, blue, bright stars typically located?

• Lower right corner
• Upper left corner
• Middle section
• Lower left corner

What is the primary process that occurs in star cores, releasing enormous amounts of energy?

• Nuclear fission
• Nuclear fusion
• Radioactive decay
• Thermal radiation

At what temperature does fusion begin in a forming star?

• 15 million K
• 5 million K
• 10 million K
• 20 million K

What happens when a star's core hydrogen fuel is depleted?

• The star immediately explodes
• The star turns into a black hole
• The core expands and cools
• The core contracts and heats up

What is the final fate of a massive star after a supernova explosion?

• White dwarf
• Red giant
• Neutron star or black hole
• Main sequence star

What characterizes the main sequence stars on the H-R diagram?

• Random scatter pattern
• Vertical line pattern
• Horizontal line pattern
• Diagonal band pattern

What happens to the outer layers of a giant star when helium is exhausted?

• They collapse inward
• They escape into space
• They freeze solid
• They become plasma

What is the defining characteristic of a black hole's event horizon?

• It emits intense radiation
• Nothing can escape from within it
• It has a visible surface
• It produces new stars

What percentage of stars do NOT fall in the main sequence?

• 25%
• 5%
• 10%
• 15%

What element is formed in the core when helium nuclei fuse?

• Oxygen
• Carbon
• Nitrogen
• Neon