Life Cycle of Stars

Question 1

During a star’s life cycle, which process is primarily responsible for creating elements heavier than iron?

Accepted Answer

Rapid neutron capture (the r‑process) that occurs during a supernova explosion.

Answer

Fusion of iron nuclei into heavier elements in the star’s core.

Answer

Slow fusion of hydrogen into helium in the star’s core.

Answer

Gradual fusion of helium into carbon during the red giant phase.

Question 2

Lily watches a time‑lapse picture where a dark, fuzzy patch in space slowly turns into a bright new star. Which sentence best describes the first step that led to the star’s birth?

Accepted Answer

The fuzzy patch was a nebula—a cloud of gas and dust that began to collapse under its own gravity.

Answer

The fuzzy patch was a planet that heated up until it started shining like a star.

Answer

The fuzzy patch was part of a galaxy that collided with another galaxy, instantly creating a star.

Answer

The fuzzy patch was a black hole that released light and turned into a star.

Question 3

Why are elements heavier than iron not produced in significant amounts during the normal fusion processes that power a star’s core?

Accepted Answer

Because fusing nuclei heavier than iron requires an input of energy rather than releasing energy, such reactions occur only during the extreme conditions of a supernova explosion.

Answer

Because iron atoms are already the most stable, they cannot combine with other nuclei to form heavier elements.

Answer

Because the temperatures in a star’s core are never high enough to fuse nuclei heavier than iron.

Answer

Because the star’s magnetic field prevents fusion of elements heavier than iron.

Try three questions

During a star’s life cycle, which process is primarily responsible for creating elements heavier than iron?

Lily watches a time‑lapse picture where a dark, fuzzy patch in space slowly turns into a bright new star. Which sentence best describes the first step that led to the star’s birth?

Why are elements heavier than iron not produced in significant amounts during the normal fusion processes that power a star’s core?

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