Interim Test (HKAGE, Jan 2022)

Arrange the following structures in ascending order of their size:

(1) Solar System (2) Galaxy (3) Star cluster (4) Nebula

• 1,2,4,3

• 1,3,4,2

• 1,4,3,2

• 2,4,3,1

A star beyond the observable universe cannot be seen. Which statements MUST be correct?

• It is not bright enough to be seen.

• The light from the star hasn't reached Earth.

• The gases and dusts between the Earth and the star absorb too much light.

There are two adult stars, A and B. If A appears bluer than B, then A must ......

• be hotter.

• be younger.

• be heavier.

• have a longer lifetime.

Universe started expanding since ____ billion years ago.

• 13.8

• 45.7

• 27.6

• 91.4

Which of the following statements about the expansion of the universe is/are correct?

• All galaxies are receding from us.

• At very large scales, the further away the galaxy, the faster it is receding from us.

• Distant galaxies show redshift in their spectral lines.

Gas and dusts in Giant Molecular Clouds begins to collapse because of ......

• its own gravitation

• nearby supernova explosion

• its own nuclear fusion

• Its temperature increases.

Star expands at the end of its adult stage because .......

• There is not much helium at its core.

• The core shrinks and this increases its temperature.

• There is a hydrogen-burning shell around the core.

White dwarf ......

• is an Earth-sized star.

• still has some nuclear fusion in its core.

• has high density and strong gravity.

The maximum mass of a white dwarf is ___ solar masses.

• 1.0

• 1.4

• 2.3

• 3

An adult star has about 4 solar masses. It will die as a ......

• Black dwarf

• White dwarf

• Neutron star

• Black Hole