Option A is the true statement about Earth's atmosphere. The Earth's atmosphere is primarily composed of nitrogen, constituting about 78% of the total volume, and oxygen, making up approximately 21%.
These two gases dominate the composition of the atmosphere and play crucial roles in supporting life and regulating climate.
Nitrogen provides stability, while oxygen is essential for respiration and combustion.
Option B is false as the Earth's atmosphere is dynamic and constantly undergoing changes.
Various natural processes, human activities, and climatic factors contribute to fluctuations in atmospheric conditions, including temperature, pressure, and composition.
Option C is false since the ozone layer is primarily located in the stratosphere, not the troposphere.
The stratospheric ozone layer plays a vital role in absorbing and filtering ultraviolet radiation from the sun.
Option D is false because the composition of the Earth's atmosphere varies with altitude.
Different layers, such as the troposphere, stratosphere, mesosphere, and thermosphere, exhibit distinct compositions and characteristics.
The probable question may be:
Which statement about earths atmosphere is true?
A. The Earth's atmosphere is composed primarily of nitrogen (about 78%) and oxygen (about 21%).
B. The Earth's atmosphere is static and does not undergo any changes.
C. The ozone layer is located in the troposphere, the lowest layer of the Earth's atmosphere.
D. The composition of the Earth's atmosphere is constant throughout all layers.