Question

which phrase describes air pressure?
decreases with denser air
decreases as altitude decreases
equals mass divided by volume
decreases as a result of fewer air particles pushing down

Explanation:

• Air pressure is the force exerted by air molecules. As altitude increases, there are fewer air particles above a given point, so air pressure decreases.
• Denser air (more molecules in a given volume) actually increases air pressure.
• As altitude decreases (going lower), air pressure increases (not decreases).
• Mass divided by volume is density, not air pressure.

Answer:

decreases as a result of fewer air particles pushing down