Concept:One of the core postulates of the Kinetic Molecular Theory (KMT) is that collisions between gas molecules, and between gas molecules and container walls (or the Earth), are perfectly elastic.
Solution:- Because the collisions are perfectly elastic, gas molecules never lose their net kinetic energy upon colliding.
- If collisions were inelastic, the molecules would slowly lose energy, slow down, and eventually succumb to gravity and settle on the ground.
- Since no kinetic energy is lost, they remain in a state of continuous, random, rapid motion, easily overcoming the downward pull of gravity and preventing the air from settling out.
Why other options are incorrect:- Option A: Different molar masses cause different rates of diffusion (Graham's Law), but this does not prevent settling.
- Option B: Polarity affects intermolecular forces, not the conservation of kinetic energy that keeps them aloft.
- Option C: Dust particles settle out of the air themselves; they do not keep gas molecules suspended.
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