Astronomy - Earth Reviewer

Greenhouse gases (water molecules and carbon dioxide) generate heat to make our Earth warm.

• True
• False

The uppermost layer of the Earth's structure is composed of mostly ____.

• silicates
• olivines
• metals
• oxygen and nitrogenoxygen and nitrogen
• All of these choices are correct.

The ozone layer protects us from

• infrared radiation.
• ultraviolet radiation.
• gamma rays.
• cosmic rays.

The composition of the Earth's atmosphere today is about 78% _____, 21% _____, and much less than 1% __________.

• oxygen; nitrogen; carbon dioxide and other gases
• nitrogen; carbon dioxide; oxygen and other gases
• oxygen; carbon dioxide; nitrogen and other gases
• nitrogen; oxygen; carbon dioxide and other gases

The Earth's core is slightly hotter than the surface of the Sun.

• True
• False

Silicates are minerals composed of silicon and oxygen.

• True
• False

The interior layer just below the crust of the Earth is called the _______.

• inner core
• outer core
• mantle
• troposphere

What causes the greenhouse effect?

• Water vapor and carbon dioxide absorb infrared radiation from the ground and reradiate the heat toward the surface.
• Water vapor and carbon dioxide absorb visible sunlight and warms the atmosphere.
• Ozone absorbs solar ultraviolet radiation and warms the atmosphere.
• Oxygen and nitrogen scatter sunlight which heats the atmosphere by its frictional passage.
• Fluorocarbons absorb infrared radiation from the Sun and heat the surface.

Magnetic fields are created by moving charged particles.

• True
• False

The early atmosphere of Earth had more methane and ammonia than what is present today. Where did these gases go?

• Sunlight broke methane and ammonia apart and the hydrogen escaped to space.
• Methane and ammonia dissolved in Earth's oceans.
• Plant life converted methane and ammonia to nitrogen and carbon through photosynthesis.
• Cometary and planetesimal impacts provided enough energy for these gases to escape to space.