Answer
See explanation
Work Step by Step
During a polytropic process, $$
\begin{aligned}
P v^n & =\text { constant } \\
T P^{(n-1) / n} & =\text { constant }
\end{aligned}
$$ and for an isentropic process, $$
\begin{aligned}
P V^k & =\text { constant } \\
T P^{(k-1) / k} & =\text { constant }
\end{aligned}
$$ If heat is lost during the expansion of the gas, $$
T_4>T_{4 x}
$$ where $T_4$ is the temperature that would occur if the expansion were reversible and adiabatic (n=k). This can only occur when $$
n \leq k
$$
