NEET 2020 Physics and Chemistry

Free expansion ⇒Pex=0
∴w=−PexΔV=0
∵ Adiabatic process ⇒q=0 also, ΔU=q+w [ first law of thermodynamics]
∴ΔU=0
∵ Internal energy of an ideal gas is a function of temperature
∴ If internal energy remains constant
∴ΔT=0