Question

p-V plots for two gases during adiabatic processes are shown in the following figure. Plots 1 and 2 should correspond respectively to

• A. $Heand{O}_2$
• B. $O_{2}andHe$
• C. $HeandAr$
• D. $O_{2}and{N}_2$

Answer 1

The correct option is B $O_{2}andHe$

In an adiabatic process,
$P{V}^{\gamma }$ = constant
differentiating both side we get, slope of P-V graph,
$=\frac{dP}{dV}=-\gamma PV$
$i.e.,$ slope~ proportional to gamma (with negative sign)
which means more the $\gamma$ more will be the slope.

In (figure) (slope) of curve 2> (slope) of curve 1
$\gamma 2>\gamma 1$
Greater the value of $\gamma$, lesser the work done.

therefore, Plot 1 corresponds to $O_2$ (lesser $\gamma )$ and Plot 2 corresponds to He(more $\gamma$)