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A light year is the amount of time it takes for light from the Sun to reach the Earth.
True
False
The ozone layer is important to human life because it protects people from:
microwaves.
gamma rays.
ultraviolet light rays.
None of the choices are correct.
UVA and UVB rays can cause skin damage and skin cancer.
True
False
Which of the following chemicals destroys the ozone layer?
CFCs
gasoline
hydrogen
All of the choices are correct.
The Milky Way is 100,000 light years in size.
True
False
All stars die out after becoming white dwarfs.
True
False
Black holes:
are the brightest objects in space.
are the most well understood objects in space.
pulse in a regular pattern.
None of the choices are correct.