Scientists can determine if oxygen existed in earth's archean atmosphere by
a. determining the lack of oxidation that occurred.
b. determining how many people survived.
c. looking at the amount of salt content in rocks.
d. looking for oxidized iron in rocks.

Which of these features are formed when hot groundwater is forced out through cracks in the earth's surface?

Which sentence from holes contains an implied personality trait? stanley and his parents had tried to pretend that he was just going away to camp for a while, just like rich kids do. he'd just been in the wrong place at the wrong time. stanley felt somewhat dazed as the guard unlocked his handcuffs and led him off the bus. stanley nodded to show he understood

To prevent the presence of air, noble gases are placed over highly reactive chemicals to act as inert "blanketing" gases. a chemical engineer places a mixture of noble gases consisting of 4.37 g of he, 13.36 g of ne, and 36.65 g of kr in a piston-cylinder assembly at stp. calculate the partial pressure in torr of kr.