A gaseous mass that envelops the earth is referred to as what?

The term used to describe the gaseous mass that surrounds the Earth is "atmosphere." This layer plays a crucial role in supporting life by providing essential gases such as oxygen and nitrogen. It also acts as a protective barrier against solar radiation and helps in maintaining the planet's temperature through the greenhouse effect. The atmosphere is composed of several layers, including the troposphere, stratosphere, mesosphere, thermosphere, and exosphere, each with distinct characteristics and functions.

While the other choices refer to specific layers within the atmosphere, they do not encompass the entire gaseous mass surrounding the Earth. For instance, the troposphere is the lowest layer where weather occurs, and the stratosphere lies above it, containing the ozone layer that absorbs harmful UV radiation. The exosphere is the outermost layer, where atmospheric particles are sparse, but none of these options fully represent the concept of the atmosphere as a whole. Thus, "atmosphere" is the most accurate term in this context.