MCQ Detailed View

Atmospheric pressure is the force exerted by the weight of air molecules in the atmosphere on the Earth's surface. This pressure is highest at sea level, where the density of air molecules is greatest due to the weight of the entire atmosphere pressing down from above. As we move upward to higher altitudes, the amount of air above decreases, leading to a reduction in atmospheric pressure.

The atmosphere is composed of gases such as nitrogen, oxygen, carbon dioxide, and trace elements, and gravity pulls these gases toward the Earth's surface. At higher altitudes, the air becomes thinner because there are fewer air molecules per unit volume. As a result, the weight of the air column decreases, and the air pressure drops.

For example, at sea level, the standard atmospheric pressure is about 101.3 kPa (kilopascals). At an altitude of 5,000 meters, the pressure significantly decreases because there is less air mass above that point. This is why people often experience breathing difficulties or shortness of breath at high altitudes—the lower pressure means less oxygen is available for each breath.

Atmospheric pressure does not increase with altitude because there is no additional air above to add weight. It also does not remain the same because gravity pulls air molecules toward the surface. The pressure continues to decrease steadily as altitude increases, and in outer space, it becomes nearly zero (a vacuum).

This principle is important in Physics and Meteorology because it explains phenomena such as weather patterns, boiling point changes at high altitudes, flight of airplanes, and human adaptation in mountainous regions.

Thus, the correct answer is Decreasing, as atmospheric pressure drops continuously with an increase in height above the Earth's surface.