Class 11 NEET Chemistry Chemical Thermodynamics

∆S=R‌ln‌V2/V1
Here the volume of gas increases from V1 to V2 at constant temperature T.
since V2>V1, it is obvious that the spontaneous (irreversible) isothermal expansion of a gas is accompanied by an increase in the entropy of the system and its surroundings considered together.
∆Ssys+∆Ssurr>0