In an adiabatic process,which of the following statements is true?

Consider a spherical shell of radius $R$ at temperature $T$. The black body radiation inside it can be considered as an ideal gas of photons with internal energy per unit volume $E = \frac{U}{V} \propto T^4$ and pressure $P = \frac{1}{3} \left( \frac{U}{V} \right)$. If the shell now undergoes an adiabatic expansion,the relation between $T$ and $R$ is:

Two moles of an ideal monoatomic gas at $27^{\circ}C$ occupies a volume of $V$. If the gas is expanded adiabatically to the volume $2V$,then the work done by the gas will be ....... $J$ $[\gamma = 5/3, R = 8.31 \text{ J/mol K}]$

The volume of a gas is reduced adiabatically to $\frac{1}{4}$ of its initial volume at $27^{\circ}C$. If the value of $\gamma = 1.4$,then the new temperature will be:

In an adiabatic expansion,the product of pressure and volume:

An ideal gas is compressed to half its initial volume by means of several processes. Which of the processes results in the maximum work done on the gas?