Which of the accompanying $PV$ diagrams best represents an isothermal process?

Write the first law of thermodynamics for an isothermal expansion process.

In isothermal expansion,the pressure is determined by

One mole of an ideal gas at $27^{\circ} {C}$ is taken from $A$ to $B$ as shown in the given $PV$ indicator diagram. The work done by the system will be $...... \times 10^{-1} \, {J}$.
[Given: $R = 8.3 \, {J} / \text{mole} \cdot {K}, \ln 2 = 0.6931$] (Round off to the nearest integer)

The specific heat of an isothermal process is:

The work done in doubling the volume of $5$ moles of an ideal gas at a constant temperature of $500 \, K$ is ....... $J$.