Which one has the lowest density at room temperature ?
Correct answer: C. NH3
- A. Ne
- B. N2
- C. NH3
- D. CO
Explanation
At the same temperature and pressure, gas density is proportional to molar mass. NH3 has molar mass 17 g mol-1, lower than Ne at about 20.2 g mol-1, N2 at 28 g mol-1 and CO at 28 g mol-1, so NH3 has the lowest density. Students may choose Ne because it is a light noble gas, but ammonia is lighter.
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About Kinetic Molecular Theory
Kinetic molecular theory explains gases as rapidly moving particles separated by large distances, with negligible volume and negligible intermolecular attraction in the ideal model. It relates temperature to average kinetic energy and explains gas pressure, Boyle's and Charles's laws, diffusion, effusion and the conditions under which real gases deviate from ideal behavior.
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