a neutron, a chroma and a tail.
a nucleus, a croma and a tail.
a nucleus, a coma and a tail.
a nucleus, a coma and a trail.

2) Pick the true statement:

New comets come from the Oort cloud.
The Oort cloud is inside the solar system.

3) How long does it take the Sun to completely melt away a comet?

1 hundred years.
1 thousand years.
1 million years.
1 billion, billion years.

4) The nucleus of the average comet is ...

one of the brightest surfaces in the solar system
one of the blackest surfaces in the solar system

5) The first close-up photographs of the nucleus of a comet (Comet Halley) were taken in 1986 by ...

the spacecraft Gotti
the spacecraft Gittio
the spacecraft Giotto

6) Which statement is false?

There are two types of comet tails: plasma tails made from ions and electrons and dusty tails made from dust particles.
The tail of a comet is either made out of rocks or out of large pieces of frozen ice.
The plasma tail of a comet is affected by the magnetic field of the solar wind.

7) Which statement is true?

Fred Whipple proposed the dirty snowball model for comets in 1650.
Dirty snowball model: A comet's nucleus is an irregularly-shaped frozen ice and dust ball.

8) Solar radiation blows the dusty tail of a comet. The solar wind blows the plasma tail.

True
False

9) Short-period comets appear every 2 years.

Correct
Not correct

10) Pick the correct average size for a comet below:

nucleus - 1 kilometres ____ coma - 100 kilometres in diameter ____ tail - 10,000 kilometres in length
nucleus - 10 kilometres ____ coma - 100,000 kilometres in diameter ____ tail - 100,000,000 kilometres in length
nucleus - 100 kilometres ____ coma - 1000 kilometres in diameter ____ tail - 100,000 kilometres in length