Answer:
Task 1:
1. The abundance of the chemical elements is a measure of the occurrence of the chemical elements relative to all other elements in a given environment.
2. The relative abundance definition in chemistry is the percentage of a particular isotope that occurs in nature.
3. Percent abundance is the percentage amount of all naturally occurring isotopes of an element.
Task 2:
Crust- Oxygen and Silicon have the most abundance with Oxygen having the most.
Hydrosphere- Hydrogen and Oxygen have the most abundance with Hydrogen having the most.
Troposphere- Nitrogen and Oxygen have the most abundance with Nitrogen having the most.
Task 3:
Potassium is part of the hydrosphere because Potassium readily dissolves in water during weathering of potassium-bearing minerals and enters the hydrosphere for a long time.
In the Troposphere the last 1% is made of argon, water vapor, and carbon dioxide.
I had to do some investigation for this but I hope this helps :)