Label the sequence of events in the evolution of the atmosphere in the correct order.

the atmosphere is thin. earth is hot due to meteorite bombardment.

eukaryotes began to form.

earth cools. water vapor condenses and oceans form.

photosynthesis by cyanobacteria reduces the level of carbon dioxide in the air. banded iron formations form in the oceans.

a thick atmosphere develops due to volcanic outgassing, shielding the surface from meteorite bombardment.

oxygen moves from the oceans to the atmosphere.

cyanobacteria evolve in the oceans and produce oxygen.

The correct order would be  

The atmosphere is thin. Earth is hot due to meteorite bombardment.  

                                           ↓

Earth cools. Water vapor condenses and oceans form.  

                                             ↓    

Cyanobacteria evolve in the oceans and produce oxygen.

                                           ↓

Oxygen moves from the oceans to the atmosphere.  

                                           ↓

Photosynthesis by cyanobacteria reduces the level of carbon dioxide in the air. Banded iron formations form in the oceans.  

                                           ↓

A thick atmosphere develops due to volcanic outgassing, shielding the surface from meteorite bombardment.  

                                           ↓

Eukaryotes began to form.  

The early atmosphere was thin and reducing (absence of oxygen). The temperature of early earth was hot due to asteroid collisions. With time the temperature of earth reduced which caused water to condense. Consequently, the oceans covered the earth surface.

After the evolution of photosynthetic cyanobacteria, the oxygen content of the atmosphere increased and carbon dioxide contents reduced.

After the presence of oxygen and thickening of the atmosphere through volcanic outgassing the origin of eukaryotic cells took place.

the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.