Extended · Practice questions · Life cycle of a star

From cloud to remnant.

Six original Cambridge-style questions on the life cycle of a star and how mass decides its fate.

Original questions All questions on this page are original work, written in the Cambridge IGCSE style. They are not from past papers. They test the same concepts and skills the syllabus rewards.

What the examiner wants

Mass decides the ending.

Shared start: nebula, protostar, main sequence.
Low mass: red giant, planetary nebula, white dwarf.
High mass: red supergiant, supernova, neutron star or black hole.

Recall

[3 marks]

Name, in order, the first three stages in the life of any star.

Nebula. ✓
Protostar. ✓
Main sequence star. ✓

Recall

[3 marks]

Describe the final stages of a low-mass star like the Sun, after the main sequence.

It becomes a red giant. ✓
It throws off its outer layers as a planetary nebula. ✓
It ends as a white dwarf. ✓

Recall

[3 marks]

Describe the final stages of a high-mass star after the main sequence.

It becomes a red supergiant. ✓
It explodes as a supernova. ✓
It leaves a neutron star, or a black hole if massive enough. ✓

Analysis

[2 marks]

Explain why a main sequence star stays the same size for a long time.

Gravity pulls the star inwards. ✓
The outward push from fusion balances gravity, so the star is stable. ✓

Application

[1 mark]

State the single property of a star that decides whether it ends as a white dwarf or as a neutron star or black hole.

Its mass. ✓

Application

[2 marks]

A student says the Sun will one day explode as a supernova. Explain why this is wrong and state what will actually happen to it.

The Sun is a low-mass star, and only high-mass stars end in a supernova. ✓
It will become a red giant, then a planetary nebula, and end as a white dwarf. ✓

Mark this once you have attempted all six and checked your working. It records a Practiced badge on the topic and adds a one-time bonus. Revealing the solutions alone does not count.