Answer: A
Explanation:
Oxygen makes up another 20 to 21 percent of our atmosphere. It's essential for life on Earth, and interestingly enough, it is poisonous when highly concentrated. Our concentration of 20 to 21 percent seems just right.
The correct answer of the given question above would be option D. The option that did not occur during the Cenozoic era is the formation of the ozone layer. The ozone layer has long been there before any era since it is part of the earth's atmosphere. Hope this answer helps.
4 is true with question you asked
Answer:
There are 4 methods by which you can increase the rate of a reaction:
Explanation:
Increase the concentration of a reactant.
Increase the temperature of the reactants.
Increase the surface area of a reactant.
Add a catalyst to the reaction.
