1. What is the basis for the division of the layers of the atmosphere surrounding earth?
a. Changing temperature.
b. Changing amount of oxygen
c. Changing weather patterns
d. changing composition of gases.

2. What happens to the surrounding air as warm air rises?
a. it moves in all directions
b. it moves to a higher altitude where warm air rises.
c. it moves away from the rising air.
d. it moves toward the place where warm air rises.​