Window to our universe

A gas that takes about 78% of the Earth's atmosphere.

• Nitrogen

• Oxygen

• Argon

• Carbon Dioxide

Mars and Venus are planets that are part of the

• inner solar system

• outer solar system

• none of the above

• Both

A gas that takes about 0.9% of the Earth's atmosphere.

• Oxygen

• Argon

• Carbon dioxide

• Nitrogen

A gas that takes about 0.03% of the Earth's atmosphere.

• Nitrogen

• Oxygen

• Argon

• Carbon dioxide

Earth, Mars and Venus all have ............. although the percentages differ.

• Nitrogen

• Oxygen

• Argon

• Carbon dioxide

A gas that takes about 21% of the Earth's atmosphere.

• Argon

• Carbon dioxide

• Nitrogen

• Oxygen

The Earth's atmosphere is about

• 300 miles thick

• 480 km thick

• Both

• None of the above