Gas Law Practice

When you put dry ice, CO2 (s), in a plastic bag, the bag puffs up. Which explanation best explains what happens to cause the bag to puff up?

• The CO2 molecules rise to the top of the container

• The CO2 molecules go to the outer edges of the bag, pushing the sides out

• The CO2 molecules spread apart from one another and bounce around inside the bag

• The CO2 molecules become larger in the gas phase compared with the solid phase

When you boil water, it turns into steam. Which explanation best explains what happens to the water molecules when liquid water becomes steam?

• The water molecules are destroyed

• The water molecules float up to the ceiling

• The water molecules float down to the floor

• The water molecules fill up the space in the room

A pine log floats on water. Which explanation best explains why this happens?

• The log is denser than water. Substances that are denser float in substances that are less dense.

• The log is less dense than water. Substances that are denser float in substances that are less dense.

• The log is less dense than water. Substances that are less dense float in substances that are denser.

• The log is denser than water. Substances that are less dense float in substances that are denser.

What phase change occurs when dew forms?

• evaporation

• condensation

• sublimation

• freezing

Which is NOT an example of a phase change?

• Condensation

• Evaporation

• Expansion

• Sublimation

Which phase of matter is least dense?

• Gas

• Solid

• All have equal densities

• Liquid

What happens to the volume and density of a gas as the gas is cooled at a constant pressure?

• Both volume and density increase

• Volume decreases and density increases

• Volume increases and density decreases

• Both volume and density decrease

Suppose a car weighs 2,500 pounds. Each of the four tires touches the road over an area that is about a 4.0 in x 4.0 in square. What tire pressure is needed in each tire to hold up the car?
(Remember: Pressure is pounds per square inch)

• 625 lb/in^2

• 78 lb/in^2

• 160 lb/in^2

• 39 lb/in^2

You washed a water bottle in hot water, and put the cap back on and went to sleep. When you woke up in the morning, the water bottle was crushed. Explain what happened to the water bottle.

• When the bottle cooled down after washing, the volume increases causing the bottle to crush.

• When the bottle cooled down after washing, the pressure inside the closed bottle became less than the pressure of air outside the bottle, so the air pressure pushed the walls of the bottle in.

• When the bottle was washed extra molecules were added inside the bottle that caused the bottle to crush.

• When the bottle cooled down after washing, the molecules inside the bottle hit the sides of the container more often causing the bottle to crush.

The force over a surface area caused by gas molecules striking the walls of a container is called:

• Heat

• Pressure

• Temperature

• Volume