Kinetic Theory

Q1.A container holds a mixture of 2 moles of He and 3 moles of N₂ at 300 K. The ratio of partial pressures P_He/P_N₂ is:

• A3:2
• B2:3
• C1:1
• D4:9

Q2.Using kinetic theory, the pressure exerted by gas molecules can be derived. The key assumption that leads to the factor 1/3 in P = (1/3)nmv² is:

• AAll molecules move with the same speed
• BMolecules only move in one direction
• CEqual number of molecules move in each of the six directions on average
• DMolecules interact with each other

Q3.The mean free path l of molecules depends on number density n and diameter d as l = 1/(√2 nπd²). If both the temperature and pressure are doubled, how does l change?

• Al doubles
• Bl halves
• Cl remains same
• Dl becomes √2 times

Q4.The RMS speed of gas molecules is given by:

• Avrms = √(2kBT/m)
• Bvrms = √(kBT/m)
• Cvrms = √(3kBT/m)
• Dvrms = √(3kBT/2m)

Q5.In a container, equal masses of helium (M = 4 g/mol) and neon (M = 20 g/mol) are mixed. The ratio of average kinetic energies per molecule of He to Ne at the same temperature is:

• A5:1
• B1:5
• C1:1
• D1:√5