Question

the envelope of gases surrounding earth is known as the atmosphere. which of the following statements accurately describes the atmosphere?

a. the atmosphere is composed entirely of nitrogen and oxygen, which react to form ozone.

b. the atmosphere is composed of masses of air particles that are constantly circulating.

c. the atmosphere is composed of masses of air particles that move very little, if at all.

d. the atmosphere is composed of several layers that increase in density as altitude increases.

Explanation:

• Option A: The atmosphere has other gases (like argon, CO₂) besides N₂ and O₂, and ozone forms from O₂ in UV, not N₂ - O₂ reaction. Eliminate A.
• Option B: Air particles in the atmosphere (due to wind, convection) circulate constantly. This matches atmospheric dynamics.
• Option C: Air particles do move (e.g., wind, atmospheric circulation), so "move very little" is wrong. Eliminate C.
• Option D: Atmospheric density decreases with increasing altitude (gravity pulls air closer to Earth), so "increase in density as altitude increases" is wrong. Eliminate D.

Answer:

B. The atmosphere is composed of masses of air particles that are constantly circulating.