Stars form from clouds of dust and gas, with gravity pulling them together into protostars. Once hot enough, they begin nuclear fusion, entering a stable main sequence phase lasting billions of years. Stars eventually die, either swelling into red giants and becoming white dwarfs or exploding as supernovae, forming neutron stars or black holes. These processes create most elements found on Earth.

What initiates the formation of a protostar?

• Nuclear fusion

• Gravitational force

• Magnetic fields

• Electromagnetic radiation

What marks the birth of a star?

• Formation of a protostar

• Cooling of the gas and dust

• Fusion of hydrogen nuclei into helium

• Expansion of the protostar

During the main sequence period, what balances the gravitational forces?

• Thermal expansion

• Magnetic fields

• Nuclear fusion

• Electromagnetic radiation

How long does the main sequence period last?

• Several thousand years

• Several billion years

• Several million years

• Several hundred years

What happens to sun-like stars when they run out of hydrogen?

• They become red giants

• They remain unchanged

• They become black holes

• They explode in supernovae

What is left behind after a sun-like star sheds its outer layers?

• A red supergiant

• A neutron star

• A black hole

• A white dwarf

What do massive stars become after they run out of hydrogen?

• Neutron stars

• Red giants

• White dwarfs

• Red supergiants

What event leads to the formation of heavier elements in massive stars?

• Formation of a protostar

• Main sequence period

• Supernova explosion

• Red giant phase

What can be the remnants of a supernova explosion?

• Neutron stars or black holes

• Protostars

• Red giants

• White dwarfs

What are stars responsible for creating?

• Only light elements

• Only hydrogen and helium

• Only heavy elements

• All elements on the periodic table