It is the manipulated variable. It is changed in an experiment to see how it would effect another variable.
Answer:
By volume, oxygen is the second most abundant element in the hydrosphere and troposphere. The troposphere is the lowest part of Earth's atmosphere which is nothing but air, and the hydrosphere is made up of the Earth's water which is full of oxygen at any given moment.
Answer:C,D,E
Explanation:I did the USA test prep
Answer: negatively; electron.
In a chemical bond, proton and neutron didn't take action since they are located in the middle(nucleus) of the atom. The electron which on the outer side of an atom can interact with another electron from an other atom/molecule. Electron has negative charge, while proton is positive and neutron is neutral.