$\therefore$ Pressure $=P=$ constant

volume is increased.

Work Done can not be jero, because volume is increased, hence $\Delta V > 0$

$W D=P \Delta V$

$W D > 0$

From, $P V=n R T$

$V \propto T$

As volume increased, Temperature also increased

So $\Delta u \neq 0$

From, first law of thermodynamics

$\Delta \theta=\Delta U+W D$

$\Delta \theta \neq 0$

Now, $V=\frac{n R}{p} T$

Differentiate both sides w.r.t. $T$

$\frac{d V}{d T}=\frac{n R}{P} \frac{d T}{d T}$

$\frac{d v}{d T}=\underbrace{\frac{n R}{P}} & \longrightarrow \text { constant }(\because \text { Isobaric) }$

Differentiate again w.r.l. $T$

$\frac{d^2 V}{d T^2}=0$