Pure Phy TYS Topic 7 Kinetic Model MCQ

Air in a closed container contains smoke, illuminated by bright light. When viewed through a microscope, bright specks of light are seen moving at random.

Which statement is correct?

• The random motion of the specks is faster in a vacuum.

• The specks move faster when the air is at a higher temperature.

• The specks seen are molecules of air in rapid random motion.

• When the light is turned off, the specks slow down and stop moving.

Smoke particles in air are illuminated by a beam of light and viewed through a microscope. The smoke particles undergo jerky random motion. What causes this motion?

• A. atomic vibrations within the smoke particles

• B. collisions between the smoke particles

• C. impacts of fast-moving air molecules

• D. the energy of the beam of light

Which row explains why a liquid has a fixed volume but does not have a fixed shape?

• A. large | move throughout the liquid

• B. large | vibrate at fixed positions

• C. small | move throughout the liquid

• D. small | vibrate at fixed positions

What happens to the molecules of mercury when it freezes?

• They attract each other more strongly.

• They expand.

• They get smaller.

• They stop moving.

Brownian motion can be observed by the behaviour of smoke particles in a smoke cell. What is this evidence for?

• A. Air is a poor conductor.

• B. Air molecules are moving.

• C. Air molecules have more mass than smoke particles.

• D. Convection occurs in air.

When smoke particles are viewed under a microscope, they can be seen moving with Brownian motion. Which row describes and explains Brownian motion?

• A. description: random, explanation: smoke particles bombard the air molecules

• B. description: random, explanation: air molecules bombard the smoke particles

• C. description: vibration, explanation: smoke particles bombard the air molecules

• D. description: vibration, explanation: air molecules bombard the smoke particles

Thermal energy is supplied continuously to water in a kettle to keep the water boiling. As the water boils, molecules escape as a vapour.

The water vapour above the water in the kettle is at the boiling point of water.

How do the molecules of water in the vapour compare with the molecules in the liquid water?

• Their average kinetic energy is greater and the force between them is smaller.

• Their average kinetic energy is greater but the force between them is the same.

• Their average kinetic energy is the same and the force between them is the same.

• Their average kinetic energy is the same but the force between them is smaller.

What is the correct order for the densities of these materials?

• A) air, aluminium, water

• B) air, water, aluminium

• C) water, air, aluminium

• D) water, aluminium, air