197. The $(P-V)$ diagram of a certain ideal gas is shown below. The internal energy of the gas at state $c$ is how many joules more than at state $a$? $\left(C_P = \dfrac{5}{2}R\right)$ [Figure: P-V diagram with pressure axis P(Pa) and volume axis V(lit). Points a and b are connected by a dashed horizontal line at pressure $10^5$ Pa. Points b and c are connected by a dashed vertical line. Point c is at volume 8 lit and pressure $10^5$ Pa. The process from a to b is isobaric (isothermal label shown), and from b to c is isochoric. The volume axis shows values 2, 5, 8 and pressure axis shows $10^5$.] \begin{align*} &(1) 450 &(2) 720 &(3) 750 &(4) 1500 \end{align*}
\textbf{197.} The $(P-V)$ diagram of a certain ideal gas is shown below. The internal energy of the gas at state $c$ is how many joules more than at state $a$? $\left(C_P = \dfrac{5}{2}R\right)$
\textit{[Figure: P-V diagram with pressure axis P(Pa) and volume axis V(lit). Points a and b are connected by a dashed horizontal line at pressure $10^5$ Pa. Points b and c are connected by a dashed vertical line. Point c is at volume 8 lit and pressure $10^5$ Pa. The process from a to b is isobaric (isothermal label shown), and from b to c is isochoric. The volume axis shows values 2, 5, 8 and pressure axis shows $10^5$.]}
\begin{align*}
&(1)\quad 450 \\
&(2)\quad 720 \\
&(3)\quad 750 \\
&(4)\quad 1500
\end{align*}