What layer of the atmosphere contains almost 80% of the atmospheres total mass

Solution:

The troposphere is the atmospheric layer closest to the planet and contains the largest percentage (around 80%) of the mass of the total atmosphere.

The troposphere is the lowest major atmospheric layer, extending from the Earth's surface up to the bottom of the stratosphere. The troposphere is where all of Earth's weather occurs. It contains approximately 80% of the total mass of the atmosphere.

The troposphere is characterized by decreasing temperature with height (at an average rate of 3.5 degrees F per thousand feet, or 6.5 degrees C per kilometer). In contrast, the stratosphere has either constant or slowly increasing temperature with height.

Thus the right answer is troposphere.