11.2

Is the following sentence true or false? As air pressure decreases, so does air density.

true

Choose the letter of each sentence that is true about air. a. Air has mass because it is composed of atoms and molecules. b. Because air has mass, it has density and pressure. c. The more molecules in a given volume of air, the greater its density. d. The greater the density of air, the less pressure it exerts.

A, Air has mass because it is composed of atoms and molecules B.,Because air has mass, C., it has density and pressure. The more molecules in a given volume of air, the greater

Why is air pressure greater at sea level than at the top of a mountain?

The air contains 21 percent oxygen, whether you are at sea level or on top of a mountain. However, since the air is less dense at a high altitude, each cubic meter of air you breathe has fewer oxygen molecules than at sea level. So you would become short of breath more quickly at a high altitude.

density

The amount of mass in a given volume of air

What is air pressure?

Air pressure is the result of the weight of a column of air pushing on an area.

Barometer

An instrument that is used to measure air pressure

altitude

Another word for elevation, or distance above sea level

What units are commonly used to measure air pressure?

Barometers and mercury barometers are commonly used to measure air pressure.

Choose the letter of the sentence that helps explain why you would have more difficulty breathing at high altitudes than at sea level. a. Air pressure is higher at high altitudes. b. Density of the air is greater at high altitudes. c. The percentage of oxygen in the air is lower at high altitudes. d. The amount of oxygen in each breath is less at high altitudes.

C. The percentage of oxygen in the air is lower at high altitudes.

Why doesn't air pressure crush objects such as your desk?

The reason that air pressure doesn't crush objects such as a desk is because that air molecules in air push all the directions, up, down, and sideways. The air pushing down on top of your desk is balanced by the air pushing up on the bottom of your desk.

Is the following sentence true or false? Air pressure increases as altitude increases.

false