Astrophysics iGCSE Edexcel

Which of the following are in the correct order of size from largest to smallest?

• galaxy, universe, planet, star

• star, planet, comet, galaxy, moon

• galaxy, universe, star, planet, moon

• universe, galaxy, star, planet, comet

What object is at the centre of our Solar System?

• a black hole

• a large star

• the Earth

• a quasar

Stars are classified based on two properties of the star. Which of the following properties are the basis of classification?

• brightness and colour

• colour and surface temperature

• brightness and surface temperature

• size and colour

Where do stars form?

• They do not form – they have been here since the beginning of the Universe.

• They form in a supernova.

• They form in stellar nebulae.

• They form from dead planets

What causes the nuclear fusion to begin in a star?

• lots of dust particles ignite

• helium molecules being produced

• intense heat and pressure

• gravity

When a star is in the main sequence, what can be said about the forces acting inside the star?

• The outward pressure is greater than the gravitational pull.

• The gravitational pull is greater than the pressure from the fusion reactions.

• All the forces acting on the star are unbalanced.

• The inward gravitational attraction is equal to the outward pressure from the fusion reactions.

How might it be noticeable that a star is now fusing helium rather than hydrogen atoms?

• The star cools and becomes a white dwarf.

• The star shrinks then expands to form a red giant.

• A black hole is created.

• The star stops glowing.

Which of the following describes how a star much greater in mass than the Sun might end its life?

• It will cool and collapse, forming a white dwarf.

• It will cool and become a neutron star.

• It will cool and become a supergiant which will then explode into a supernova, leaving a black hole.

• It will remain stable for too long for us to know what might happen.

The brightness of a star depends on two factors. Which of the following shows the two factors?

• the luminosity of the star and its distance from the Earth

• the size of the star and its colour

• the luminosity of the star and its size

• the colour of the star and its surface temperature

Which of the following correctly identifies the absolute brightness of a star?

• the brightness of the star as seen from the Earth

• the amount of light emitted per second by the star

• the brightness of the star compared to other stars if all stars were the same distance from the Earth

• the colour of the star