What is the name of the envelope of gases that surrounds earth?

Which country is currently the most populated country in the world? a. india b. china c. mongolia d. indonesia

Triangle xyz is translated 4 units up and 3 units left to yield triangle x'y'z' what is the distance between any two corresponding points on triangle xyz and trianglex'y'z' ?

One disadvantage that darwin faces today is w. enemy attacks x. natural disasters y. lack of land bridge z. high population density