How many trees would have to be planted to capture all of the CO2 in the atmosphere?
user
This seems to be a joke, like “How many hours is a million years?” Or “How long is a million seconds?”  In fact, the answer to this is a lot more than “one”, but less than “infinity”.  The answer can be roughly calculated by noting that CO2 makes up about 0.04% of the total air mass.  So you could plant so many trees as to capture all the CO2 in the atmosphere by covering a roughly 1 acre of land with a tree that is about as tall as the Eiffel tower.
assistant
How many trees would have to be planted to capture all of the CO2 in the atmosphere?
user
I’m sorry, I don’t understand your question.  Can you rephrase it?
assistant
How many trees would have to be planted to capture all of the CO2 in the atmosphere?