Air pressure decreases with altitude. In fact, by assuming that air has the same temperature at all altitudes, it is possible to derive the law of atmospheres:

p = p0e–h/a,

where p0 denotes the air pressure at sea level, h denotes the altitude above sea level, a denotes a constant, and p denotes the pressure at height h. For instance, many people have difficulty breathing on Mt. Everest, due in part to the lower air pressure.

1. | According to the law of atmospheres, which graph best expresses the relationship between air pressure and altitude above sea level?

A. | A

B. | B

C. | C

D. | D

2. | At sea level, where the air pressure is 1 atm, a glass container is filled with air at –40° C, and sealed shut. The container is taken to Mt. Everest, where the temperature is –40° C. The pressure of the air in the container is now:

A. | more than 1 atm

B. | about 1 atm

C. | less than 1 atm

D. | We cannot determine the answer without more information

3. | At sea level, a flexible balloon is partially filled with –40° C air, to a volume of 1 liter. The leak-proof balloon is taken to Mt. Everest, where the temperature remains –40° C. Which of the following is true about the pressure (p) and volume (V) of the air inside the balloon?

A. | p » 1 atm, V > 1 liter

B. | p < 1 atm, V > 1 liter

C. | p > 1 atm, V > 1 liter

D. | p < 1 atm, V < 1 liter

4. | Which of the following is a reason why real gases deviate from the ideal gas law?

A. | Mutual attractions between molecules slow them down as they approach the walls of the container.

B. | Collisions between the molecules and the walls of the container are usually inelastic.

C. | Molecules collide not only with the sides of the container, but also with each other.

D. | In a gas, different molecules have different speeds.

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