How can humans impact the environment in a negative way

How many ions that have a +1 charge will bond with an ion that has a -2 charge

What are the spectator ions in 2h+ + so42- + ca2+ + 2r → caso4 + 2h+ + 21?

Although respiratory organs vary across different organisms, they all contain respiratory surfaces that have a large surface area and are extremely thin. explain why having an extremely thin respiratory surface with a large surface area is advantageous for the process of gas exchange