The most plentiful chemical elements found in the Sun and the gas giants are...

• hydrogen and helium
• nitrogen and oxygen
• carbon dioxide and nitrogen
• hydrogen and methane

Compared to the terrestrial planets of the inner Solar System, the gas giants contain mainly ____________ gases in their atmospheres.

• heavier gases
• lighter gases
• inert gases (not chemically active)
• reactive gases

Which two terrestrial planets have atmospheres dominated by carbon dioxide CO₂?

• Mercury and Earth
• Mercury and Mars
• Venus and Mars
• Venus and Earth

Among the terrestrial planets, Earth's atmosphere is exceptional because...

• it contains low amounts of nitrogen N₂.

• it has a high % of argon Ar.

• it has a high % of oxygen and a low % of carbon dioxide.

• it has a large % (>10%) of greenhouse gases.

The relatively high % of oxygen O₂ in Earth's atmosphere is primarily due to....

• a biological process.
• the rock cycle.
• Earth's gravity.
• Earth's magnetic field.

Earth's first atmosphere was composed of high amounts of...

• nitrogen and oxygen
• carbon dioxide and nitrogen
• hydrogen and helium
• methane and argon

The two primary greenhouse gases that moderate Earth's climate today are ...

• carbon dioxide and water vapor

• nitrogen and ozone

• nitrogen and argon

• hydrogen and helium

The factor that moderates the amount of carbon dioxide in Earth's atmosphere to the least degree is _______________.

• the presence of large oceans
• photosynthesis
• human activity
• the formation of rocks by deposition

Determine the most correct statement about the origin of planetary atmospheres in our Solar System regarding their current composition.

• The terrestrial planets captured their atmospheres from leftover gas in space.

• The terrestrial planets (except one) formed and retained their current atmospheres from volcanic outgassing.

• Comet impacts brought the materials for generating atmospheres.

• The atmospheres came from the solar wind.

The factor having little or no consequence regarding Mars' substantial loss of atmosphere over time is...

• its cold temperature
• solar wind erosion
• its low gravity
• its lack of a magnetic field