Question
Smoke particles, illuminated by a bright lamp, 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
Answer/Explanation
Ans:
B
Question
In an experiment, smoke particles are suspended in air and viewed through a microscope.
The smoke particles move about with short random movements. Which of the following statements is correct?
A Air particles have large masses compared to smoke particles and they move in one directiononly.
B Air particles have large masses compared to smoke particles and they move in random directions.
C Air particles move at high speeds compared to smoke particles and they move in one direction only.
D Air particles move at high speeds compared to smoke particles and they move in random directions.
Answer/Explanation
Ans: D
Question
Which row describes the forces between the molecules and the motion of the molecules in a gas?
| forces between molecules | motion of molecules |
A | strong | move freely |
B | strong | vibrate only |
C | weak | move freely |
D | weak | vibrate only |
Answer/Explanation
Ans: C
Question
Very small pollen grains are suspended in water. A bright light shines from the side.
When looked at through a microscope, small specks of light are seen to be moving in a random, jerky manner.
What are the moving specks of light?
pollen grains being hit by other pollen grains
pollen grains being hit by water molecules
water molecules being hit by other water molecules
water molecules being hit by pollen grains
Answer/Explanation
Ans: B
Question
When pollen grains in water are viewed through a microscope, they are seen to be in continuous, rapid random motion.
What causes a pollen grain to move in this way?
-
-
convection currents in the water
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bombardment by a single molecule of water
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uneven bombardment on different sides by water molecules
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collision with another pollen grain due to their kinetic energies
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