Review 8th

The __________ is a thin layer of gases surrounding Earth.

• Atmosphere

• Mesosphere

• Estratosphere

• Troposphere

Earth’s atmosphere contains a layer of __________ that helps keep

temperatures on Earth within a range that living organisms can survive.

• Oxygen

• Gases

• Nitrogen

• Carbon dioxide

Earth’s atmosphere helps protect living organisms from some of the _____________ harmful rays.

• Atmosphere's

• Sunlight's

• Sun's

• Earth's

Earth’s ancient atmosphere formed from hot __________ that escaped from Earth’s hardening surface.

• Rock

• Gases

• Acid

• Water

As Earth’s atmosphere cooled, the water vapor condensed into a(n)

__________ that fell as rain. Over thousands of years, the rain

formed Earth’s __________.

• Oceans

• Water

• Liquid

• Crust

Organisms that use photosynthesis produced the __________ in today’s atmosphere.

• Carbon dioxide

• Gases

• Energy

• Oxygen

Nitrogen makes up about __________ percent of Earth’s atmosphere.

• 21%

• 78%

• 18%

• 31%

Oxygen makes up about __________ percent of Earth’s atmosphere.

• 75%

• 35%

• 18%

• 21%

Volcanoes send __________ and liquid acids into the atmosphere.

• Ashes

• Dust

• Rock

• Gases

Where weather occurs

• Troposphere

• Estratosphere

• Exosphere

• Thermosphere