Clicker Questions Chapter 14: Gases © 2015 Pearson Education, Inc

Clicker Questions

© 2015 Pearson Education, Inc.

Chapter 14: Gases

© 2015 Pearson Education, Inc.

Molecules that make up Earth's atmosphere don't fly off into outer space because of

a) their relatively high speeds.

b) their low densities.

c) Earth's gravitation.

d) the Sun's influence.

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Molecules that make up Earth's atmosphere don't fly off into outer space because of

a) their relatively high speeds.

b) their low densities.

c) Earth's gravitation.

d) the Sun's influence.

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Atmospheric pressure is caused by the atmosphere's

a) density.

b) weight.

c) temperature.

d) response to solar energy.

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Atmospheric pressure is caused by the atmosphere's

a) density.

b) weight.

c) temperature.

d) response to solar energy.

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The higher one goes in the atmosphere, the less the

a) atmospheric pressure.

b) density of air.

c) Both of these.

d) None of these.

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The higher one goes in the atmosphere, the less the

a) atmospheric pressure.

b) density of air.

c) Both of these.

d) None of these.

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Pulling apart a pair of evacuated Magdeburg hemispheres would be easier

a) at high altitudes.

b) at low altitudes.

c) beneath the surface of a lake.

d) None of these makes a difference.

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Pulling apart a pair of evacuated Magdeburg hemispheres would be easier

a) at high altitudes.

b) at low altitudes.

c) beneath the surface of a lake.

d) None of these makes a difference.

Explanation: Atmospheric pressure is what one pulls against, which is less at high altitudes. So the task of pulling the hemispheres apart is easier there. Beneath the surface of a lake you contend with both water pressure and atmospheric pressure, so the task there is even greater.

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The weight of a 1-square-meter column of air extending from sea level to the "top" of the atmosphere weighs about

a) 100 N.

b) 10,000 N.

c) 100,000 N.

d) 100,000,000 N.

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The weight of a 1-square-meter column of air extending from sea level to the "top" of the atmosphere weighs about

a) 100 N.

b) 10,000 N.

c) 100,000 N.

d) 100,000,000 N.

Explanation: Atmospheric pressure at sea level is roughly 105 N/m2, about 101 kPa. So over each square meter is some 101,000 N of air.

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Consider two tubes 30 km tall. One is filled with air and the other is partially filled with water. The weight of fluid in each will be the same when the level of water in the water tube is

a) 10.3 m high.

b) 76 cm high.

c) 760 mm high.

d) None of these.

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Consider two tubes 30 km tall. One is filled with air and the other is partially filled with water. The weight of fluid in each will be the same when the level of water in the water tube is

a) 10.3 m high.

b) 76 cm high.

c) 760 mm high.

d) None of these.

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A barometer can be used to measure

a) atmospheric pressure.

b) altitude.

c) Both of these.

d) None of these.

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A barometer can be used to measure

a) atmospheric pressure.

b) altitude.

c) Both of these.

d) None of these.

Explanation: A barometer used to measure altitude is called an aneroid barometer.

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A simple barometer will be tallest if it uses

a) mercury.

b) water.

c) gasoline (which is less dense than water).

d) any of these liquids, for the height would be the same at sea level.

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A simple barometer will be tallest if it uses

a) mercury.

b) water.

c) gasoline (which is less dense than water).

d) any of these liquids, for the height would be the same at sea level.

Explanation: Of these liquids, least-density gasoline would be tallest, an equal-diameter column of which would have to weigh as much as 76 cm of mercury or 10.3 m of water.

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Liquid pumps operate due to differences in

a) pressure.

b) densities of fluids.

c) viscosities of fluids.

d) energies.

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Liquid pumps operate due to differences in

a) pressure.

b) densities of fluids.

c) viscosities of fluids.

d) energies.

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An old-fashioned farm water pump would work best

a) in low-lying regions.

b) in mountainous regions.

c) if on the Moon.

d) on freezing cold-days.

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An old-fashioned farm water pump would work best

a) in low-lying regions.

b) in mountainous regions.

c) if on the Moon.

d) on freezing cold-days.

Explanation: Such pumps operate by way of atmospheric pressure and are therefore best suited to low-lying regions where atmospheric pressure is greater.

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When you squeeze an air-filled party balloon you reduce its

a) volume.

b) mass.

c) weight.

d) All of these.

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When you squeeze an air-filled party balloon you reduce its

a) volume.

b) mass.

c) weight.

d) All of these.

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When you squeeze an air-filled party balloon you increase its

a) volume.

b) mass.

c) weight.

d) density.

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When you squeeze an air-filled party balloon you increase its

a) volume.

b) mass.

c) weight.

d) density.

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Consider a steel tank used for storing gas. If you pump enough helium into the tank, it

a) may float like a balloon.

b) will bear down with less force on the floor.

c) Both of these.

d) None of these.

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Consider a steel tank used for storing gas. If you pump enough helium into the tank, it

a) may float like a balloon.

b) will bear down with less force on the floor.

c) Both of these.

d) None of these.

Explanation: A helium-filled balloon is able to float only because its volume increases enough to displace its own weight of surrounding air. The steel tank has a fixed volume. The more helium pumped into it, the heavier it becomes.

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A helium-filled balloon hovers in air. The pressure of the atmosphere against the bottom of the balloon must be

a) greater than pressure against the top.

b) equal to the pressure on top.

c) less than the pressure on top.

d) None of these.

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A helium-filled balloon hovers in air. The pressure of the atmosphere against the bottom of the balloon must be

a) greater than pressure against the top.

b) equal to the pressure on top.

c) less than the pressure on top.

d) None of these.

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If a hot-air balloon hovers at a fixed altitude, the net weight of the balloon must be

a) slightly less than the weight of displaced air.

b) equal to the weight of displaced air.

c) slightly greater than the weight of displaced air.

d) None of these.

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If a hot-air balloon hovers at a fixed altitude, the net weight of the balloon must be

a) slightly less than the weight of displaced air.

b) equal to the weight of displaced air.

c) slightly greater than the weight of displaced air.

d) None of these.

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When wind flows from a valley and over the tops of hills, the speed of the wind is greater

a) in the valley.

b) on top of the hills.

c) on the downside of the hills.

d) nowhere in particular, for air speed isn't affected by hills.

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When wind flows from a valley and over the tops of hills, the speed of the wind is greater

a) in the valley.

b) on top of the hills.

c) on the downside of the hills.

d) nowhere in particular, for air speed isn't affected by hills.

Explanation: The principle of continuity tells us that where an air path is narrower, as on top of a hill, air speed must increase.

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As water in a confined pipe speeds up, the pressure it exerts against the inner walls of the pipe

a) increases.

b) decreases.

c) remains constant if flow rate is constant.

d) None of these.

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As water in a confined pipe speeds up, the pressure it exerts against the inner walls of the pipe

a) increases.

b) decreases.

c) remains constant if flow rate is constant.

d) None of these.

Explanation:

Straight Bernoulli!

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Compared with the pressure within the water coming from a fire hose, the water pressure that can knock over a shed is

a) less.

b) the same.

c) more.

d) nonexistent.

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Compared with the pressure within the water coming from a fire hose, the water pressure that can knock over a shed is

a) less.

b) the same.

c) more.

d) nonexistent.

Explanation: Distinguish between the pressure in the water and the pressure water can exert of something that reduces its momentum.

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If air speed is greater along the top surface of a bird's wings, pressure of the moving air there is

a) unaffected.

b) less.

c) more.

d) turbulent.

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If air speed is greater along the top surface of a bird's wings, pressure of the moving air there is

a) unaffected.

b) less.

c) more.

d) turbulent.

Explanation: Straight Bernoulli!

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The main difference between hot gases and a plasma involves

a) interatomic spacing.

b) fluid pressure.

c) minute quantities of antimatter.

d) electrical conduction.

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The main difference between hot gases and a plasma involves

a) interatomic spacing.

b) fluid pressure.

c) minute quantities of antimatter.

d) electrical conduction.

Explanation: A property of a plasma is that it can conduct electricity.