NEET2026PhysicsChapterActual
A sealed container holds a gaseous mixture of Neon ( Ne ), Oxygen ( O₂ ), and Carbon dioxide ( CO₂ ) in thermal equilibrium at a constant temperature. Which of the following statements is correct regarding the root mean square (rms) speed of the molecules in this mixture?
Options
- AThe rms speed of CO₂ molecules is the greatest.
- BAll molecules have the same rms speed because the mixture is in thermal equilibrium.
- CThe rms speed of Neon molecules is the greatest.
- DThe rms speed of Oxygen molecules is less than that of CO₂ molecules.
Correct answer
C. The rms speed of Neon molecules is the greatest.
Step-by-step solution
The root mean square (rms) speed of gas molecules is given by the formula: v_ rms = 3RT M where R is the universal gas constant, T is the absolute temperature, and M is the molar mass of the gas. Since the gaseous mixture is in thermal equilibrium, the temperature T is the same for all the gases. Therefore, the rms speed is inversely proportional to the square root of the molar mass: v_ rms 1 M The molar masses of the given gases are: M_ Ne = 20 g/mol M_ O₂ = 32 g/mol M_ CO₂ = 44 g/mol Comparing the molar masses: M