Four curves A, B, C and D are drawn in the given figure for a given amount of gas. The curves which represent adiabatic and isothermal changes are :

Answer & explanation
Correct answer: option 3
As we know that slopes of isothermal and adiabatic curves are always negative ad slope of adiabatic curve is always greater than that of isothermal curve, in the give graph curve A and curve B represent adiabatic and isothermal changes, respectively.