<u>Answer :</u>
Part 13:
The balanced chemical reaction will be:

Part 14:
The balanced chemical reaction will be:

Part 15:
The balanced chemical reaction will be:

<u>Explanation :</u>
Balanced chemical reaction : It is defined as the reaction in which an individual element of an atom present on reactant side must be equal to product side.
Part 13:
The balanced chemical reaction will be:

Part 14:
The balanced chemical reaction will be:

Part 15:
The balanced chemical reaction will be:

Because if all the trees and grasslands are to disappear and turn into deserts then there would be no oxygen for us
Think, does a chemical reaction take place? Do the rocks and/or the water undergo any chemical changes?
Answer:
143 parts I think probably not
Its going to be 2.81 x 1023 atoms