Stars, Fusion & Element Formation — Drills · Grade 9 Science

Chapter: Stars & the Universe

What these drills covers

By the end of Stars, Fusion & Element Formation you should be able to:

8 questions, multiple choice and written answer, each with a worked explanation.

Vocabulary used: fusion, main sequence, white dwarf.

Problem 1

The Sun is expected to leave which remnant after its later stages?
  1. White dwarf
  2. Earth-sized planet with oceans
  3. Neutron star in every case
  4. A second Sun of identical mass
Answer and explanation

White dwarf

Its mass is too low for the usual massive-star collapse pathway.

Problem 2

Are all elements produced by exactly the same stellar process?
Answer and explanation

No. Production pathways depend on element and conditions; heavy-element formation can involve processes beyond ordinary stellar fusion.

Problem 3

A star's energy comes from
  1. burning like a fire
  2. nuclear fusion in its core
  3. friction
  4. chemical reactions
Answer and explanation

nuclear fusion in its core

Fusion of light nuclei into heavier ones releases energy.

Problem 4

In a main-sequence star, fusion mainly converts
  1. hydrogen into helium
  2. helium into hydrogen
  3. iron into gold
  4. carbon into oxygen
Answer and explanation

hydrogen into helium

Hydrogen fusion powers stars for most of their lives.

Problem 5

A more massive star generally lives
  1. longer
  2. shorter
  3. the same time
  4. forever
Answer and explanation

shorter

It has more fuel but burns it far faster, so its lifetime is shorter.

Problem 6

Elements heavier than iron are formed mainly
  1. in ordinary main-sequence fusion
  2. in supernovae and similar extreme events
  3. in planets
  4. in comets
Answer and explanation

in supernovae and similar extreme events

Fusion to iron releases energy; beyond iron it absorbs energy, so extreme conditions are needed.

Problem 7

Explain the statement that the atoms in your body were made in stars.
Answer and explanation

Hydrogen formed early in the universe, but carbon, oxygen, nitrogen and the heavier elements in living tissue were produced by fusion inside stars and dispersed when those stars died. That material became part of later clouds from which the Sun and planets formed. The claim is literal: the elements were manufactured in stellar interiors before Earth existed.

Response criteria

  • State a scientifically accurate conclusion.
  • Show the data, mechanism, or calculation that supports it.
  • Include units, conditions, or limits where relevant.

Problem 8

Why does a star remain stable for billions of years rather than collapsing or exploding?
Answer and explanation

Gravity pulls inward while the pressure from energy released by fusion pushes outward, and the two balance. If fusion slows the star contracts, which raises the core temperature and speeds fusion again; if it runs too fast the star expands and cools. That self-correcting balance is a negative feedback, and it holds until the fuel the star depends on runs out.

Response criteria

  • State a scientifically accurate conclusion.
  • Show the data, mechanism, or calculation that supports it.
  • Include units, conditions, or limits where relevant.

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