Structure of Matter and Kinetic Theory
Physics · 50 practice questions
Molecular nature of matter — atoms and molecules, molecular theory (Brownian motion, diffusion, surface tension, capillarity, adhesion, cohesion, angle of contact); kinetic theory — its assumptions and use in explaining gas pressure, Boyle's and Charles' laws, melting, boiling, vaporization, temperature change and evaporation.
- Differentiate between atoms and molecules and use molecular theory to explain Brownian motion, diffusion, surface tension, capillarity, adhesion, cohesion and angle of contact.
- Examine the assumptions of kinetic theory and interpret it in relation to gas pressure, Boyle's law, Charles' law and changes of state.
Try a few questions
- Practice question 1
Brownian motion provides mainly indirect evidence for the
- A.existence of electric charge within a substance
- B.existence of magnetic fields around a substance
- C.exact chemical formula of a substance
- D.existence of molecules and their constant, random motion
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D. existence of molecules and their constant, random motion
Since we can't directly see molecules, their effect on visible particles offers strong indirect proof of their random motion.
- Practice question 2
Kinetic theory explains gas pressure as arising from the
- A.constant bombardment of gas molecules on the walls of their container
- B.complete absence of any molecular motion within the gas
- C.attractive forces pulling gas molecules toward the container walls
- D.weight of the gas pressing directly downward only
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A. constant bombardment of gas molecules on the walls of their container
Repeated molecular collisions against the container walls are what physically produce measurable gas pressure.
- Practice question 3
A liquid's surface behaves somewhat like a stretched elastic skin due to surface tension, which arises from the
- A.equal cohesive forces experienced by all molecules, both at the surface and within the bulk liquid
- B.complete absence of any cohesive forces at the liquid's surface
- C.unequal cohesive forces experienced by surface molecules compared to those within the bulk liquid
- D.adhesive forces between the liquid and the surrounding air alone
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C. unequal cohesive forces experienced by surface molecules compared to those within the bulk liquid
This imbalance, with surface molecules lacking neighbours above them, produces the net inward pull responsible for surface tension.
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