It is believed that the planet Mars has a much thicker carbon dioxide atmosphere in the past than it does today. Where the bulk of this carbon dioxide go?
A) it reacted with surface rocks
B) it condensed to form the polar caps
C) it was destroyed in the atmosphere through chemical reactions
D) it was lost into space
Question 2
Each of the following describes an Atom 1 and an Atom 2. In which case are the two atoms isotopes of each other?
A) Atom 1: nucleus with 6 protons and 8 neutrons, surrounded by 6 electrons
Atom 2: nucleus with 7 protons and 8 neutrons, surrounded by 7 electrons
B) Atom 1: nucleus with 8 protons and 8 neutrons, surrounded by 8 electrons
Atom 2: nucleus with 8 protons and 8 neutrons, surrounded by 7 electrons
C) Atom 1: nucleus with 92 protons and 143 neutrons, surrounded by 92 electrons
Atom 2: nucleus with 92 protons and 146 neutrons, surrounded by 92 electrons
D) Atom 1: nucleus with 1 proton and 0 neutrons, surrounded by 1 electron
Atom 2: nucleus with 2 protons and 2 neutrons, surrounded by 2 electrons
E) Atom 1: nucleus with 4 protons and 5 neutrons, surrounded by 4 electrons
Atom 2: nucleus with 5 protons and 5 neutrons, surrounded by 4 electrons
Extent of agricultural activity across the planet (data from Foley et al. 2005).
Animation of the apparent retrograde motion of Mars in 2003 as seen from Earth
Iron in the Sun’s Atmosphere
The Atmosphere’s Oxygen Came from Photosynthetic Organisms
Vertical Structure of the Atmosphere
Stomatal density and carbon dioxide