Answer:
180 hope this helps tell me if its wrong
Explanation:
Answer:
oxygen: it was the result of biological activities. There were such stable continental shelf environments, which were rare in the Archean, developed after 2.5 billion years ago, facilitating the growth of photosynthetic organisms and thus oxygen production.
Answer:
Because, Air (or any gas) takes up space in water, just like solids. Air (or any gas) is less dense than water, so gas bubbles float to the top of water.
It is the variable being controlled/changed to see if there are any effects on the dependent variable (the thing getting tested/measured)
