Question 139: Thermodynamics & KTG

Question

Given below are two statements. One is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) :
With the increase in the pressure of an ideal gas, the volume falls off more rapidly in an isothermal process in comparison to the adiabatic process.
Reason (R) :
In isothermal process, PV = constant, while in adiabatic process $PV^{\gamma}$ = constant. Here $\gamma$ is the ratio of specific heats, P is the pressure and V is the volume of the ideal gas.
In the light of the above statements, choose the
correct
answer from the options given below:

Accepted Answer

We know, ideal gas equation,
$\mathrm{Pv = nRT}$
For isothermal process, T = constant
$\mathrm{\Rightarrow PV = const.}$
$\mathrm{\Rightarrow P \propto \frac{1}{V}}$
For an adiabatic process,
$\mathrm{PV^r=constant}$
We can see, for the same pressure incresement, $${P_2} - {P_1}$$, $$\left( {{v_4} - {v_3}} \right) > \left( {{v_2} - {v_1}} \right)$$
i.e. the volume falls off more rapidly in an isothermal process in comparison to the adiabatic process. Hence, option 4 is corret.

Answer

(A) is true but (R) is false

Answer

Both (A) and (R) are true but (R) is NOT the correct explanation of (A)

Answer

(A) is false but (R) is true

Answer

Both (A) and (R) are true and (R) is the correct explanation of (A)

Thermodynamics & KTG

Choose the correct answer: