thermal effects

2 The diagram shows four beakers A, B, C and D. The beakers contain different amounts of the same liquid at the same temperature. The beakers are left next to each other on a laboratory bench overnight. The diagrams are all drawn to the same scale.

From which beaker does the largest quantity of liquid evaporate?

• A

• B

• C

• D

Tags

NGSS.MS-PS1-4

2 Gases can be compressed, but liquids cannot.

Which statement explains this difference?

• Each molecule in a gas is more compressible than each molecule in a liquid.

• Molecules in a gas are further apart than molecules in a liquid.

• Molecules in a gas attract each other more strongly than molecules in a liquid.

• Molecules in a gas move more slowly than molecules in a liquid.

Smoke particles, illuminated by a bright light, are seen through a microscope. They move about randomly.

What causes this motion?

• attraction between the smoke particles and the molecules of the air

• collisions between the smoke particles and the molecules of the air

• evaporation of the faster-moving smoke particles

• warming of the smoke particles by the lamp

2 A beaker contains 0.500 kg of water at a temperature of 3.0 °C. The beaker is heated, and the internal energy of the water increases by 21.0 kJ.

The specific heat capacity of water is 4200 J / (kg °C).

What is the temperature of the water after it has been heated?

• A 5.5 °C

• B 10.0 °C

• C 13.0 °C

• D 31.5 °C

2 Evaporation occurs when molecules escape from a liquid surface into the air above it. During this process the temperature of the liquid falls.

Why does the temperature of the liquid fall?

• The molecules in the vapour expand because the pressure is less

• The molecules left in the liquid have more space to move around.

• The molecules with the highest energies escape into the air.

• The molecules move more slowly when they escape into the air.

2 Some air is trapped inside a metal can with a tightly fitting lid.

When the can is heated strongly behind a safety screen, the lid is blown off by the increased pressure inside the can.

What causes the increase in pressure of the air inside the can?

• The air molecules expand and take up more room.

• The volume occupied by the molecules decreases.

• The number of molecules inside the can increases.

• The air molecules move more quickly.

The molecules of a substance become more closely packed and move more quickly.

What is happening to the substance?

.

• A gas is being heated and compressed.

• A gas is being heated and is expanding.

• A liquid is boiling

• A liquid is evaporating at room temperature.

A closed flask of gas is placed in a cold-water bath.

As the flask cools, the temperature of the gas decreases. What happens to the molecules of the gas?

• They contract.

• They expand.

• They move more slowly.

• They move more quickly.

A sealed jar containing a gas.

Which statement about the gas in the jar is correct?

• The gas molecules collide with the inside of the jar more often as the temperature increases.

• The pressure of the gas is higher at the top of the jar than at the bottom of the jar.

• The pressure of the gas decreases as the temperature increases.

• The gas molecules move more slowly as the temperature increases.

2 Which diagram best shows the path of a gas molecule?

• A

• B

• C

• D

Tags

NGSS.HS-PS2-1

NGSS.HS-PS3-2