Can $PV = RT$ be described with an isothermal or an adiabatic process?

When an ideal gas is compressed isothermally,its pressure:

An isothermal process has a non-linear graph between:

$A$ cylinder fitted with a piston contains $0.2 \, moles$ of air at a temperature of $27^{\circ}C$. The piston is pushed so slowly that the air within the cylinder remains in thermal equilibrium with the surroundings. Find the approximate work done by the system if the final volume is twice the initial volume (in $J$).

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)

Two ideal gases $A$ and $B$ of the same number of moles expand at constant temperatures $T_1$ and $T_2$ respectively such that the pressure of gas $A$ decreases by $50 \%$ and the pressure of gas $B$ decreases by $75 \%$. If the work done by both the gases is same, then $T_1: T_2$ is: