Will every atom of the same type element have the exact same number of neutrons, explain why or why not?

Can someone me with these questions plz.

How have the greenhouse gasses increased from the year 2000 to 2018

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