Which of the following statements about kinetic theory of matter is not correct?

• A. The molecules of matter are always in motion
• B. When a body is heated the average kinetic energy of its molecules decreases
• C. Molecules of a liquid move more freely than those of a solid
• D. Matter is made up of very tiny particles called molecules

Which of the following properties of waves is exclusive to transverse waves?

• A. reflection
• B. interference
• C. diffraction
• D. polarization

Explain why mercury does not wet glass while water does.

Which of the following statements correctly explains why a total solar eclipse would be seen by people on only a small portion of the earth's surface? The

• A. moon is larger in diameter than the earth
• B. eath is larger in diameter than the sun
• C. earth revolves around the sun
• D. earth is larger in diameter than the moon.

In a school compound a girl walks 40km due east from the laboratory to the staff room to submit her report. Then she returns and walks 30m due north to her classroom. Determine the magnitude of her displacement from the10m laboratory

• A. 10m
• B. 35m
• C. 50m
• D. 70m

A radioactive substance has a half-life of 20 hours. What fraction of the original radioactive nuclei will remain after 80 hours?

• A. 1/32
• B. 1/16
• C. 1/8
• D. 1/4

What happens when a gas expands at constant temperature?

• A. its pressure decreases
• B. the total momentum of its molecules remains constant
• C. its pressure decreases and the total momentum of its moleculees remains constant
• D. its pressure decreses and the total kinetic energy of its molecule decreases

Which of the following statements is correct about the effect of dissolved salt on the freezing point of water?

• A. the freezing point is lowered
• B. the freezing point is increased
• C. there is no change in the freezing point
• D. the change in the freezing point depends on the temperature of the surrounding

A force of 10 N, acting continuously, increases the kinetic energy of an object from 20.J to 60 J. Find the distance moved by the object.

• A. 200m
• B. 40m
• C. 4m
• D. 400m

A piece of wood floats inside water at room temperature with a fraction of it above the liquid surface. As the temperature of the water is raised, the part of the wood above the liquid will

• A. decrease because the density of water decreases with temperature
• B. increase because the density of water decreases with temperature
• C. decreases because the density of water increases with water temperature
• D. increase because the density of water increases with temperature