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Question: Answered & Verified by Expert
An ideal gas (γ=1.5) is expanded adiabatically. How many times its initial volume should the gas be expanded to reduce the root mean square velocity of molecules by a factor of 2?
PhysicsThermodynamicsJEE Main
Options:
  • A 4 times
  • B 16 times
  • C 8 times
  • D 2 times
Solution:
2200 Upvotes Verified Answer
The correct answer is: 16 times
vrms=3RTM            or              vrmsT

vrms is to reduce two times, i.e. the temperature of the gas will have to reduce four times or

T'T=14

During the adiabatic process,

TVγ-1=T'V'γ-1

or V'V=TT'1γ-1

          =411.5-1=42=16

V'=16 V

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