Q.

The correct option for free expansion of an ideal gas under adiabatic condition is           [2020]

1 q=0, ΔT=0 and w=0  
2 q=0, ΔT<0 and w>0  
3 q<0, ΔT=0 and w=0  
4 q>0, ΔT>0 and w>0  

Ans.

(1)

For free expansion of an ideal gas, Pex=0,

w=-PexΔV=0

For adiabatic process, q=0

According to the first law of thermodynamics,

ΔU=q+w

As internal energy of an ideal gas is a function of temperature,

ΔU=0,    ΔT=0