Heat and Temperature

A party shop delivers helium-filled balloons to homes and businesses. The owners realize from experience that on hot summer days they should inflate the balloons only three-quarters full. On cold winter days they can fully inflate the balloons. Which of the following is the best hypothesis to explain this observation?

• The helium gas is more active in the winter season.

• Air outside the balloons leaks into the balloons.

• As the temperature increases, the helium in the balloons expands

• Outdoor air pressure in the summer is less than indoor air pressure

Perfume sprayed from a bottle spreads more easily in a warm room of 25°C than in a cool room of 15°C. Which of the following correctly compares perfume molecules at 25°C to those at 15°C?

• At 25°C, they have more mass

• At 25°C, they are moving faster

• At 25°C, they have less kinetic energy.

• At 25°C, they are decreasing in volume

Two boxes, A and B, both contain the same number of nitrogen gas molecules.
The gas molecules in box A have twice the average speed of the molecules in box B. Which of the following best describes the nitrogen gas in box A?

• The nitrogen gas in box A has a greater mass than the nitrogen gas in box B

• The nitrogen gas in box A has a greater density than the nitrogen gas in box B

• The nitrogen gas in box A has a greater temperature than the nitrogen gas in box B.

• The nitrogen gas in box A has a greater specific gravity than the nitrogen gas in box B

In a copper wire, a temperature increase is the result of which of the following?

• an increase in the size of the copper particles

• a decrease in the mass of the copper particles

• an increase in the motion of the copper particles

• a decrease in the distance between the copper particles

The illustration below shows a student bending a piece of wire back and forth at a single point X. The wire’s temperature rises noticeably at point X.

• Some of the wire’s mass is transformed into heat energy as the wire is bent.

• Some of the kinetic energy is transformed into heat as the wire is bent

• The bending transfers potential energy to the wire, heating it.

• The bending causes a current that heats the wire

Which of the following changes occurs as a solid is heated?

• The kinetic energy of the solid decreases

• The average density of the solid increases.

• 
  The specific heat capacity of the solid decreases.

• The average molecular speed in the solid increases

If heat is added to a liquid, which of the following occurs?

• The friction in the liquid increases

• The size of the liquid molecules expands

• The potential energy of the liquid changes

• The molecular motion in the liquid increases

Measurements inside a sealed container show that the pressure exerted by a gas increases as the thermal energy of the gas increases. Which of the following best explains this pressure increase?

• The gas molecules stick to the walls of the container

• The gas molecules radiate energy in the form of nuclear particles

• The gas molecules begin to bond together into heavier molecules

• The gas molecules move faster and strike the container walls more frequently

A heated rock is placed in a container of water that is cooler than room temperature. Which of the following statements best describes what happens?

• Cold is removed from the container of water until the rock, the container, and the water all reach the same final temperature.

• The heated rock loses heat to the container of water until the rock, the container, and the water all reach the same final temperature

• The heated rock loses heat to the container of water until the rock, the container, and the water each reach a different final temperature

• Cold is removed from the container of water until the rock, the container, and the water each reach a final temperature lower than their original temperatures

 

Which of the following statements best explains why there is no change in temperature once thermal equilibrium between two objects in contact is reached?

• Heat can flow between two objects in contact.

• Heat does not flow between objects in contact at the same temperature

• Heat does not flow spontaneously from a cooler object to a warmer object

• Heat flows by conduction, convection, and radiation when the temperatures are the same