# The below graph shows the behaviour of 3 gases undergoing adiabatic expansion. Which of the following can be true?

$\begin{array}{1 1} \text{gas1:diatomic, gas2: triatomic, gas3: monoatomic} \\ \text{gas1:triatomic, gas2: diatomic, gas3: monoatomic} \\ \text{None of these } \\ \text{gas1: monoatomic, gas2: diatomic, gas3: triatomic} \end{array}$

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• The mathematical equation for an ideal gas undergoing a reversible (i.e., no entropy generation) adiabatic process is $PV^{\gamma} =$ constant.
Given the above graph, we can see that the larger the volume of gamma, greater the slope.
Since $\large \gamma_{monoatomic} > \gamma_{diatomic} > \gamma_{triatomic}$, triatomic has the least slope, followed by diatomic and then monoatomic.
Therefore, gas1: triatomic, gas2: diatomic and gas3: monoatomic.